Danger from the Deep, often abbreviated as DftD, is an open-source World War II German U-boat simulation for PC, striving for technical and historical accuracy.

[2] The game targets Multi-platform, supporting FreeBSD, OpenBSD,[3] Mac OS X,[4] Linux distributions, and Microsoft Windows by utilizing SDL and OpenGL.

[6] The last downloadable release was May 8, 2010[7] A Linux Journal review from 2010 received DftD quite positive.

[1] In 2004 The Wargamer recommended the game to "serious sim gamers" which should "head over to Danger from the Deep's official web site and take a look.".

[2] In 2011 an Ars Technica article on the history of simulation games noted Danger from the Deep as: "These days, submarine sims [...] are kept alive by the open-source Danger from the Deep".