UB-88 was laid down in February 1917 at Hamburg, Germany, by the Aktiengesellschaft Vulcan; launched on 11 December 1917; and placed in commission in the Imperial German Navy on 26 January 1918, Oberleutnant zur See Johannes Ries in command.
After shakedown in the North and Baltic Seas, UB-88 was assigned to the / U-Flotille Flandern (1st Submarine Flotilla, Flanders) at Zeebrugge on the Belgian coast. She departed Kiel, Germany, on 4 June and headed via the eastern route, around Denmark and through the Skaggerak, south to Zeebrugge. During the voyage to her first duty station, the submarine scored her first victory. Passing down the east coast of England on the 10th, she encountered a convoy of five freighters and six trawlers escorted by two destroyers and a pair of aircraft. In a submerged attack, she fired a single torpedo which struck and sank the 1,555-ton Swedish steamer SS Dora. The convoy's escorts conducted a brief depth charge attack, but UB-88 escaped with negligible damage. Two days later, she arrived safely in Zeebrugge and reported for duty with I U-Flotille Flandern.
Between June and October, UB-88 conducted three war cruises out of Zeebrugge. The first-along the east coast of England-began when she put to sea on 20 June. On the third day out, she encountered a southbound convoy between Flamborough Head and Sunderland. She made a submerged torpedo attack and succeeded in sinking another Swedish steamer, the 1,624-ton SS Avance. The following day, the U-boat ran into another south-bound convoy, numbering about 30 ships. One of those ships rammed her main periscope, but the submarine managed a successful submerged attack using her secondary periscope and sank the 1,706-ton British ship SS London. The convoy's escorts answered with nine depth charges, but the submarine managed to evade their attacks. During the pre-dawn hours of 25 June, she encountered and sank another British steamer, the 4,482-ton SS African Transport. The 25th was UB-88's lucky day for, that evening, she ran onto a 20-ship convoy heading south. The U-boat sank SS Moorlands and then survived a 16-charge depth bombing by the convoy escorts.
Four days later, UB-88 scored another double in one day. Just before sunrise, she made a surface torpedo attack and sank the small British steamer SS Sixth Six. Near dusk that evening, she singled SS Florentia out of a north-bound convoy and sank her in another surface torpedo attack. Two days later, she concluded the cruise at Zeebrugge.
On 29 July, the submarine put to sea again to hunt Allied merchant shipping in the English Channel. While operating between Le Havre and the Isle of Wight, she encountered two steamers escorted by a French destroyer and launched two torpedoes. One hit the 6,045-ton British steamer SS Bayronto while the other missed completely. Though damaged, Bayronto made it into port because the French destroyer prevented UB-88 from finishing off her victim by barraging her with 45 depth charges. Two days later, off Brest, the submarine met a large American convoy bound for France. UB-88 attempted to maneuver into position for a submerged torpedo attack, but the convoy changed course and foiled her efforts. Shortly before the convoy entered port at Brest, the four escorting cruisers parted company with it and made for the open sea. In so doing, they presented a target that the U-boat's commander could not pass up. She fired a torpedo at one of the warships, but it missed its mark. For her impertinence, UB-88 suffered a staggering depth-charge barrage of 15 to 20 minutes in duration. She sustained severe concussion damage to her electrical system, but prompt and efficient damage control enabled her to remain in action and to continue the patrol.
The following day, she scored her third daily double. Operating to the south of Brest, she came upon a south-bound convoy escorted by armed trawlers and sporting observation balloons. The U-boat drew a bead on SS Lake Portage and fired a torpedo at the 1,998-ton American ship, which sank soon thereafter. Later, she singled SS Berwind, another American ship, out of a north-bound convoy and sank her with a single torpedo. The following day, another north-bound convoy crossed her path. In a submerged attack, UB-88 torpedoed and sank a 1,901-ton Norwegian steamer, SS Hundvaago. She rounded out that cruise with one last attack on 9 August during the return voyage to Zeebrugge. The submarine scored a torpedo hit on the 4,090-ton British ship SS Anselma de Larringa near the mouth of the Seine River. Although damaged, her victim succeeded in reaching a friendly port. UB-88 continued her homeward voyage and reentered Zeebrugge on 11 August.
After almost a month of preparations, the U-boat returned to sea on 7 September for her final cruise as a unit of / U-Flotille Flandern. Following a long voyage through the North Sea, around the Orkney Islands, and down the west coast of Ireland, she reached her operations area off the northern part of France's west coast on 14 September. Two days later, she claimed her first victim of the patrol when she fired the torpedo which sank SS Philomel, a 3,050-ton British steamer travelling south in convoy with about 19 other ships. Three days later, she fired two torpedoes at a 30-ship convoy. Apparently both missiles hit the same ship, SS Fanny, a 1,484-ton Swedish steamer bound from England to Bordeaux with a cargo of 1,930 tons of coal. The following day, she began her long return voyage to Zeebrugge via the same route, around the British Isles and through the North Sea. En route home, shortly after midnight on 22 September, she encountered her last target, SS Polesley. In a surfaced attack, UB-38 scored a torpedo hit which sent the 4,221-ton British steamer to the bottom just off the coast of Cornwall. The submarine then resumed her course and entered Zeebrugge on 29 September. She remained there only overnight. The next day, she got underway to return to Germany. On 3 October, she arrived in Heligoland and joined her new unit // U-Flotille, Hochseeftotte (2d Submarine Flotilla, High Seas Fleet). She remained inactive, first at Heligoland and, then, at Wilhelmshaven, through the end of World War I.
Soon after the 11 November armistice ended hostilities, UB-88 surrendered along with the other warships of the High Seas Fleet. They were interned, probably at Harwich, England, on 26 November 1918. When the United States Navy expressed an interest in acquiring several German submarines to be used in conjunction with the current Victory Bond drive and to enable American crews to learn their supposed secrets, UB-88 and five other boats were allocated to the United States with the agreement that they would be destroyed upon the conclusion of the bond campaign. Naval personnel were dispatched from the United States early in 1919, and they took over the warship on 23 March 1919. Soon thereafter, UB-88 was placed in special commission for the voyage across the Atlantic, Lt. Cmdr. Joseph L. Nielson in command.
After a brief period allotted to the crew to make repairs and familiarize themselves with the foreign submarine's machinery, UB-88 stood out of Harwich on 3 April in company with Bushnell (Submarine Tender No. 2) and three other former German U-boats: U-117, UC-97, and UB-U8. That task unit, dubbed the Ex-German Submarine Expeditionary Force, steamed via the Azores and Bermuda to New York, where it arrived on 27 April. Not long after reaching New York, UB-88 and the other four boats became the center-stage attraction for a horde of tourists, reporters, and photographers, as well as for technicians from the Navy Department, submarine builders, and eo,uipment suppliers. During her stay in New York, UB-88 received additional refurbishment in preparation for her participation in the bond drive.
Finally, orders arrived dispersing five of the six U-boats to different sections of the American coasts and waterways for visits to various ports along the way. UB-88 drew the longest itinerary of the five U-boats. She was assigned to the ports on the east coast south of Savannah, Ga.; ports on the Gulf coast; the Mississippi River as far north as Memphis, Tenn.; and the west coast. She departed New York on 5 May in company with her tender, the Coast Guard ship Tuscarora. On the first part of the cruise, she visited Savannah, Jacksonville, Miami, and Key West. At the time she departed Key West, the submarine had to bid farewell to Tuscarora, because boiler trouble forced the cutter to remain there for repairs. Bittern (Minesweeper No. 36) became her tender and escorted the U-boat through the remainder of her voyage.
From Key West, UB-88 headed for Tampa, thence to Pensacola; and on to Mobile and New Orleans. At the latter port, she entered the Mississippi River. For the next month, she made calls at ports large and small along the great river. Though her schedule originally called for her to travel as far north as St. Louis, Mo., she made it only as far as Memphis before the rapidly-falling water level forced her to cut short her voyage on the Mississippi and head downriver. UB-88 returned to New Orleans on 1 July and entered drydock for repairs to her port tail shaft. The submarine completed repairs on 22 July and departed New Orleans to begin a cruise to ports along the Texas coast and thence to the Canal Zone. A breakdown between Houston, Tex., and Colon, Canal Zone, meant that Bittern had to tow the submarine the final 200 miles into Colon. After receiving repairs, provisions, and visitors, UB-88 transited the canal on 12 August. Following a two-day visit to Balboa, she headed north along the Mexican coast to San Diego and, after stops at Acapulco and Man-zanillo in Mexico, reached her destination on 29 August.
The last leg of her voyage took the submarine north to San Pedro, Santa Barbara, Monterey, and San Francisco in California; Astoria and Portland in Oregon; and Seattle, Tacoma, and Bremerton in Washington. On the return voyage, she stopped at San Francisco only, departing that port on 6 November for the submarine base at San Pedro, where she arrived the next day. After being laid up at San Pedro for four months, UB-88 began the dismantling process on 1 April 1920. That operation was completed by 31 August, and UB-88 was placed out of commission on 1 November 1920. The following spring, the U-boat returned to sea for the last time; and, on 1 March 1921, she took her final plunge when Wickes (DD-75) sank her with gunfire.