The Israeli navy is a bit of an odd duck. It’s designed largely for coastal and eastern Mediterranean warfare. But among all of Israel’s small corvettes and missile boats are some some seriously mighty submarines.

Israel is also investing heavily in growing its submarine fleet. It’s a reflection of Tel Aviv’s increasing reliance on the underwater boats for a range of operations — including nuclear deterrence.

Right now, three Dolphin II-class submarines are under construction at Germany’s ThyssenKrupp Marine Systems shipyards in Kiel. Once the submarines complete their trials and head towards the Mediterranean, they will become the most powerful Israeli submarines ever.

More than 225 feet long, the diesel-electric Dolphin II class is part attack submarine, part nuclear strike ship and part commando taxi.

They’re also painted in an unusual combination of black, blue and green colors. That’s “meant to make the ship less visible, and thought to be especially effective in Mediterranean waters,” Defense News noted after recently publishing new photographs of the fat, oddly-shaped boats in dry dock and on sea trials.

In terms of weapons, the three boats of the Dolphin II class—the Tannin, Rahav and a third unnamed submarine—contain 10 torpedo tubes capable of launching fiber optic cable-guided DM-2A4 torpedoes. Germany has already handed over the Tannin, which is preparing for its journey to Israel.

Four of these tubes are larger 26-inch tubes—the size is rare for a Western-built submarine—capable of launching small commando teams or firing larger cruise missiles. The remaining six tubes measure at 21 inches.

Although not admitted by the Israeli government, the Dolphin II is widely believed to soon possess nuclear-tipped Popeye Turbo cruise missiles. The submarine’s armament includes non-nuclear anti-ship Harpoon and anti-helicopter Triton missiles.

In 2012, German news magazine Der Spiegel interviewed several German defense ministry officials, all of whom were under the assumption that Israel intends for these submarines to carry nuclear weapons. The missiles can also be launched “using a previously secret hydraulic ejection system,” the magazine reported.

The photographs at Defense News also reveal horizontal planes for trailing communications gear and sonar buoys. But the classified propeller is covered by a tarp to keep out prying eyes.