The Dolphin-class is actually two related sub-classes of diesel-electric submarine developed and constructed by Howaldtswerke-Deutsche Werft AG (HDW), Germany for the Israeli Navy. The first three members of the class were based on the export-only German 209-class submarines, but greatly modified and enlarged, and are thus not designated as members of the 209 family. The Dolphin 1 sub-class is slightly larger than the German Navy Type 212 in length and displacement. The three newer air-independent propulsion equipped boats are similar to the Type 212 vessels currently used by the German navy in underwater endurance, although the AIP Dolphins are 12 metres longer and are nearly 500 tonnes heavier in submerged displacement, and have a larger crew than either the Type 212 or the Type 214. Th