| Year | Date | Historical Events |
| 1938 | Apr 18 | Keel laid down by the Electric Boat Co., Groton, CT. |
| 1939 | Apr 21 | Launched. |
| | Oct 23 | Commissioned with LT. John G. Johns in command.
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| 1940 | May 23 | Following a shakedown cruise off the east coast and in the Caribbean Sea, Seadragon returned to New England, and departed New London, CT., for the Philippine Islands.
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| | Nov 30 | With Commander, Submarine Division 17 embarked, Seadragon arrived at Cavite, Philippine Islands, and commenced training operations as a unit of the Asiatic Fleet. |
| 1941 | Dec 8 | Seadragon started her yard period at the Cavite Navy Yard, Cavite, Phillipine Islands.
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| | Dec 10 | Seadragon and sister ship Sealion, moored together, were caught in an enemy air raid against Cavite. Sealion took a direct hit which demolished her and damaged Seadragon. |
| | Dec 10 | (Cont'd.) A nearby torpedo shop went up and flames reached toward a lighter, loaded with torpedoes, lying alongside Seadragon. Submarine Rescue Vessel Pigeon, however, disregarded the danger and moved in to tow Seadragon into the channel. |
| | Dec 10 | (Cont'd.) Seadragon continued into Manila Bay under her own power.Temporary repairs were accomplished by tender Canopus and Pigeon.
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| | Dec 15 | Seadragon embarked members of the Asiatic Fleet staff. |
| | Dec 16 | Seadragon headed out of Manila Bay, escorted by the destroyer Bulmer. Seadragon moved south, via Surigao and Makassar Straits to Soerabaja, where she disembarked her passengers, received further repairs, and prepared for her 1st war patrol.
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| | Dec 30 | Seadragon departed the Dutch naval base on her 1st war patrol, and set a course for the South China Sea to intercept Japanese shipping off the coast of Indochina. |
| 1942 | Jan 10 | Seadragon sighted a destroyer, fired 2 torpedoes which missed, then watched as the destroyer continued on it's course without attempting to attack. Seadragon remained in the area. Shortly after noon, a convoy was heard. |
| | Jan 10 | (Cont'd.) One-half hour later, it was sighted, and Seadragon began closing the last ship in the column. Shortly after 1300, she fired and missed, and again tried to close to firing position. Within an hour, the convoy was safely into Cam Ranh Bay. |
| | Feb 13 | Seadragon arrived at Soerabaja. |
| | Feb 21 | Seadragon left for Tjilatjap, whence she was ordered on to Australia. |
| | Mar 4 | Seadragon reached Fremantle, Australia. |
| | Mar 18 | Seadragon again headed for the Indochina coast for her 2nd war patrol. |
| | Mar 31 | Seadragon was diverted to Cebu to take on fuel and food for Corregidor. She unloaded ten torpedoes and 250 rounds of 3-inch ammunition, and took on thirty tons of food. |
| | Apr 8 | Seadragon moored alongside Pigeon, to which she transferred fuel, offloaded seven tons of food, and took on 23 passengers, including the last 17 members of the crew at CAST (Cryptanalysts and Traffic Analysts) |
| | Apr 11 | Seadragon she sighted several targets but was able to attack only one. She fired 3 torpedoes. Twenty nine seconds later the first torpedo exploded halfway to the target. The second broached and circled abeam of the target. The destroyer avoided the third. |
| | Apr 26 | Seadragon returned to Fremantle, Australia. |
| | Jun 11 | Seadragon returned to the South China Sea on her 3rd war patrol. |
| | Jun 27 | Arriving in her assigned area, Seadragon patrolled along the Singapore-Hong Kong routes to the end of the month, then shifted to the Cape Varella area. |
| | Jul 4 | Seadragon fired a torpedo at the leader of a 3 ship formation. The torpedo missed ahead. All 3 ships changed course toward Seadragon with the leader proceeding down the torpedo track firing her bow gun. Depth charges were dropped indiscriminately. |
| | Jul 4 | (Cont'd.) A few hours later, she sighted 2 freighters and fired tubes 1 and 2 at the lead ship. Her No. 1 tube did not fire, and her No. 2 torpedo missed astern. Two more torpedoes were fired at the ships, but both missed. |
| | Jul 11 | Seadragon's losing streak ended. Just prior to midnight, she sighted smoke and opened out to the Westward to overtake the target. |
| | Jul 12 | Seadragon began her approach, and she fired 3 torpedoes. Two hit, but the third missed astern. A merchantman, Hiyama Maru, began settling. |
| | Jul 13 | Seadragon torpedoed and sank her second victim of the patrol. Shinyo Maru was hit approximately 50 feet abaft the beam and settled immediately. Seadragon moved out of the area and hunted along the Haina Varella routes for a few days. |
| | Jul 16 | Seadragon was back off Cape Varella. She fired on a 4 ship convoy. Five minutes later, the torpedoes exploded on the beach. The four ships turned toward Seadragon and commenced firing their guns. |
| | Jul 16 | (Cont'd.) Seadragon fired 2 more torpedoes and went deep. A few minutes later, she came to periscope depth. Only 3 ships remained on the surface. Hakodate Maru had been sunk. |
| | Aug 2 | Seadragon returned to Fremantle, Australia. |
| | Aug 26 | Sedragon departed her Australian base for her 4th war patrol and again set a course for the coast of Indochina. |
| | Sep 11 | Seadragon's progress into the South China Sea was delayed by an emergency appendectomy performed successfully on Seaman Darrell Rector by Pharmacist's Mate Wheeler B. Lipes, the first such performed on a submarine. |
| | Sep 11 | (Cont'd.) This incident was the subject of a Pulitzer Prize-winning account by Chicago Daily News reporter George Weller. In 2005, retired LCDR. Lipes was awarded the Navy Commendation Medal for saving a fellow crewman's life.
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| | Sep 22 | Seadragon fired 4 torpedoes at a cruiser escorted by 2 destroyers. No explosions were heard, but her torpedoes were seen, and the enemy ships turned on Seadragon and delivered a "well executed depth charge attack."
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| | Sep 29 | Seadragon tracked a 5 ship convoy. |
| | Sep 30 | Seadragon conducted a surface torpedo attack which damaged one ship. |
| | Oct 3 | Seadragon departed the South China Sea. |
| | Oct 8 | Seadragon commenced patrolling the approaches to Balikpapan. |
| | Oct 10 | Seadragon attained a position for a stern tube shot on the Shigure Maru. The cargoman disappeared 47 seconds after the first explosion. |
| | Oct 11 | Seadragon patrolled off Cape William and Cape Mandar. |
| | Oct 12 | Seadragon was off Makassar City. |
| | Oct 14 | Seadragon transited Lombok Strait. |
| | Oct 20 | Seadragon returned to Fremantle, Australia. |
| | Nov 23 | Refit was started by submarine tender Holland at Fremantle and completed by tenders Griffin and Fulton at Brisbane. Seadragon departed the latter and headed for the Bismarck Archipelago for her 5th war patrol. |
| | Nov 29 | Seadragon entered her area and commenced patrolling the Rabaul-Shortland routes. |
| | Dec 1 | Seadragon closed the New Britain coast to intercept traffic to the Japanese beachhead at Buna, and during the next 10 days, conducted several unsuccessful approaches on enemy formations. |
| | Dec 11 | Seadragon sighted a freighter with one escort rounding Cape St. George and fired 2 torpedoes at the merchantman. One hit under the main mast, damaging but not sinking the target. |
| | Dec 21 | Seadragon sighted an enemy submarine near Cape St. George, and fired 3 torpedoes. The first missed ahead. The second exploded about 18 seconds after firing. The third torpedo hit the target. Japanese submarine I-4 sank with her bow vertical. |
| | Dec 25 | Seadragon damaged another cargoman. |
| | Dec 26 | Seadragon departed the area for Pearl Harbor, HI. |
| 1943 | Jan 7 | Seadragon arrived at Pearl Harbor, HI. From Pearl Harbor, HI. Seadragon continued on to the West Coast, where skipper "Pete" Ferrall was detached to the Bureau of Ships. |
| | Jan 16 | Seadragon underwent overhaul at Mare Island Naval Shipyard, Vallejo, CA., receiving new batteries and radar and changing the position of her three-inch mount from aft to a forward position. |
| | Apr 15 | Seadragon sailed west again. |
| | May 9 | Seadragon departed Pearl Harbor, HI. for her 6th war patrol.
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| | May 15 | Seadragon, now under Royal L. Rutter, crossed the 180th meridian and moved toward Micronesia. |
| | May 19 | Seadragon commenced patrolling in the Caroline Islands. |
| | May 20 | Seadragon surprised and was in turn surprised by sighting a surfaced submarine on a parallel course. The other submarine submerged immediately. |
| | May 22 | Seadragon took up station off the Truk Islands and for the next 11 days patrolled the sea lanes to the major enemy anchorage enclosed by Dublon, Fefan, and Uman islands. |
| | Jun 4 | Seadragon departed Truk and moved Eastward to reconnoiter Ponape, thence proceeded into the Marshall Islands to patrol the sealanes converging on Kwajalein. |
| | Jun 13 | Seadragon was able to damage a freighter. |
| | Jun 17 | Seadragon cleared the area. |
| | Jun 21 | Seadragon arrived at Midway Island, whence she returned to Pearl Harbor, HI. for repairs to her steering gear.
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| | Jul 18 | Seadragon commenced her 7th war patrol. Of the 44 days, 31 were spent on station near Wake and in the Marshall Islands where increased enemy air activity again hindered hunting and limited Seadragon's score to five freighters damaged. |
| | Aug 15 | Seadragon reconnoitered Wotje. |
| | Aug 30 | Seadragon returned to Pearl Harbor, HI. |
| | Sep 24 | On her 8th war patrol, Seadragon again returned to the Marshall Islands and spent 31 days hunting in the sea lanes to Kwajalein. |
| | Oct 13 | Seadragon damaged an enemy transport.
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| | Nov 5 | Seadragon ended her 8th war patrol. |
| | Dec 14 | Seadragon's 9th war patrol, took her back to the Caroline Islands where she hunted enemy shipping on the Truk-Saipan route and damaged 2 , possibly 3 , cargomen.
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| 1944 | Feb 5 | Seadragon ended her 9th war patrol at Pearl Harbor, HI. |
| | Apr 1 | Refit brought the replacement of Seadragon's 3 inch deck gun with a 4 inch. Seadragon cleared Pearl Harbor, HI. for the Japanese home islands for her 10th war patrol, with James H. Ashley, Jr., in command. |
| | Apr 5 | Seadragon crossed the International Date Line. |
| | Apr 15 | Seadragon entered Japanese waters. |
| | Apr 16 | Seadragon moved past O Shima, and, that night, commenced patrolling off the Bungo Strait and Kii Channel entrances to the Inland Sea. |
| | Apr 23 | Seadragon sighted 4 freighters, escorted by 3 patrol boats, moving toward Shiono Misaki. She closed the convoy, fired on the third ship, the heaviest laden, then went deep and rigged for depth charging. |
| | Apr 23 | (Cont'd.) The patrol boats moved toward Seadragon as Daiju Maru sank and, during the next two hours, delivered a 40 depth charge attack. Later that day, Seadragon conducted an unsuccessful attack on a naval auxiliary. |
| | Apr 26 | Seadragon moved out into the Tokyo-Manila shipping lanes. |
| | Apr 27 | Seadragon damaged a freighter. |
| | Apr 28 | Seadragon commenced patrolling the Nagoya-Saipan route. |
| | May 1 | Seadragon took station off the entrance to Sugura Wan. |
| | May 3 | Seadragon shifted to the Tokyo-Guam-Saipan-Truk sea lanes. |
| | May 5 | Seadragon hunted enemy traffic at the entrance to Sagami Wan. |
| | May 13 | Seadragon headed for Midway Island. |
| | May 17 | Seadragon caught an armed trawler in a surface attack, set it afire with 4 inch gun salvos, then closed the target to take off the uniformed enemy crew. The surviving crew members refused to surrender, and Seadragon continued Eastward. |
| | May 21 | Seadragon crossed the 180th meridian and stopped at Midway Island, then got underway for Pearl Harbor, HI. |
| | May 25 | Seadragon arrived at Pearl Harbor, HI. |
| | Sep 7 | Re-engined at Mare Island Naval Shipyard, Vallejo, CA. during the summer, Seadragon returned to Pearl Harbor, HI. |
| | Sep 23 | Seadragon departed on her 11th war patrol. A coordinated patrol with submarines Shark (SS-314) and Blackfish (SS-221). |
| | Oct 3 | Seadragon arrived at Saipan, Marianas Island to top off fuel. |
| | Oct 4 | Shark and Blackfish continued on to the wolfpack's assigned area in the Northern China Sea. |
| | Oct 5 | Seadragon departed Saipan, Marianas Island after being delayed for repairs. |
| | Oct 9 | Seadragon arrived off Batan Island, established contact with Shark and Blackfish, and took position in a scouting line in the pack's assigned area.
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| | Oct 22 | The group went after an enemy warship formation lead by an aircraft carrier. |
| | Oct 24 | Shark reported a contact, and Seadragon headed for the scene. The contact was sighted through the high periscope, but it proved too distant. Seadragon sighted 3 enemy merchantmen in a loose column with a torpedo boat destroyer and an airplane as escorts. |
| | Oct 24 | (Cont'd.) Seadragon fired 4 torpedoes at the lead freighter. The first torpedo broached and ran erratic, alerting the escort which started for Seadragon. Seadragon rigged for depth charging. Soon thereafter, two torpedo explosions were heard.
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| | Oct 24 | (Cont'd.) Seadragon went to periscope depth. The escort was milling around picking up survivors four miles astern. The remaining merchant ships were ahead of the submarine and making only two or three knots. |
| | Oct 24 | (Cont'd.) As Seadragon prepared to fire again, the destroyer rejoined the formation. Seadragon fired 3 more torpedoes. 3 hits were observed. The submarine's second target of the day sank in less than two minutes. |
| | Oct 24 | (Cont'd.) Seadragon returned to periscope depth. The deck of the remaining freighter was crowded. The escort circled the freighter. Seadragon fired. The first torpedo tore off the freighter's bow. The rest of the ship sank quickly. |
| | Oct 24 | (Cont'd.) Seadragon tried unsuccessfully to raise Shark. She had been sunk after attacking the contact. Postwar examination of records identified the sunken ships as the cargo ship, Eiko Maru, and the passenger-cargomen Taiten Maru and Kokuryu Maru. |
| | Oct 26 | Seadragon headed toward Luzon. |
| | Oct 27 | On 27 October and 28 October, Seadragon searched for downed aviators. |
| | Oct 29 | Seadragon was ordered to return to Midway Island.
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| | Nov 8 | Seadragon arrived at Midway Island. |
| | Dec 3 | Seadragon headed West for her 12th war patrol. The patrol took her back into Japanese waters where she hunted enemy shipping and searched for downed aviators into January 1945. |
| 1945 | Jan 10 | Seadragon moved into the Bonin Islands, where she continued those two roles. |
| | Jan 19 | Seadragon set a Southerly course. |
| | Jan 22 | Seadragon arrived at Guam, Marianas Island, to complete her last war patrol.
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| | Jan 23 | Seadragon continued on to Pearl Harbor, HI. and, after refit, returned to California to provide training services to naval air units. |
| | May 1 | Seadragon was transferred back to the Atlantic Fleet and for the final months of the war, provided training services at Guantanamo Bay, Cuba and Key West, FL. |
| | Sep 1 | Seadragon moved north to New London, CT., thence to Boston, MA., where she was decommissioned. |
| | Nov 15 | Decommissioned at Boston, MA. |
| 1946 | Feb 8 | Seadragon was recommissioned to assist in the inactivation and preservation of submarines, including U-boats, at Hingham, MA. |
| | Oct 29 | Seadragon was again decommissioned and berthed as a unit of the Atlantic Reserve Fleet. |
| 1948 | Apr 30 | Struck from the Naval Register. |
| | Jul 2 | Seadragon was sold for scrap. |