| Date | Location | Name | Deaths | Description |
| 1781-11-29 29 November 1781, et seq | Caribbean Sea, east of Jamaica | Zong massacre | 0,000,132 132–142 | In order to claim on insurance, 132 to 142 African slaves were thrown overboard when potable water ran low. |
| 1917-04-08 8 April 1917 | Western Approaches, 150 miles south-west of Scilly | SS Torrington | 0,000,034 34 | After torpedoing Torrington, U-55s commander took the crew on deck and sank their lifeboats, then submerged, leaving them to drown. One crew member survived. |
| 1918-06-27 27 June 1918 | Western Approaches, 116 miles west of Fastnet | Llandovery Castle | 0,000,234 234 | After torpedoing a Hospital ship, contrary to international law, U-86 rammed and sank lifeboats, firing on survivors. 24 crew escaped. |
| 1940-08-23 8 August 1940 | Central Atlantic, 800 miles west of Canary Islands | SS Anglo Saxon | 0,000,039 39 | After sinking Anglo Saxon, German raider Widder fired on the lifeboats. One escaped, two crew survived. |
| 1943-03-4 4 March 1943 | Indian Ocean | SS Tjisalak | 0,000,105 105 | After torpedoing Tjisalak, Japanese submarine I-8 took the survivors on board, then beat them to death. |
| 1940-08-23 18 March 1943 | Pacific Ocean, Bismarck Sea | Akikaze | 0,000,039 ~60 | The destroyer Akikaze picked up German missionaries from New Guinea and was ordered by 8th Fleet command to execute them all. |
| 1944-03-13 13 March 1944 | South Atlantic | SS Peleus | 0,000,032 32 | After torpedoing Peleus, U-852 fired on survivors clinging to wreckage. Three survived. |
| 1917-04-08 18 March 1944 | Indian Ocean, off Tanjung Priok | SS Behar | 0,000,104 104–108 | After sinking Behar, Japanese cruiser Tone took the crew on board, then later killed them by beheading. Four men escaped. |
| 1944-03-26 26 March 1944 | Pacific Ocean, Bismarck Sea | Bismarck Sea Massacre | 2,890+ | After destroying a Japanese convoy, Allied boats and planes attacked Japanese rescue vessels, as well as survivors on life rafts and swimming or floating in the sea. |
| 1985-05-155 May 1985 | Jaffna District, Sri Lanka | Kumudini boat massacre | 0,000,023 23 | Kumudini boat massacre, massacre of 23 Tamil civilians by the Sri Lankan Navy in the sea off Jaffna District, Sri Lanka. |
| 1993-01-02 2 January 1993 | Jaffna District, Sri Lanka | Jaffna lagoon massacre | 0,000,038 38 | Jaffna lagoon massacre, massacre of 38 Tamil civilians by Sri Lankan Navy in the sea off Jaffna District, Sri Lanka. |