U.S. Special Operations Command has inked a $166 million contract with Lockheed Martin to provide dry combat submersibles designed to transport operators to their mission sites underwater.

The surface-launched mini-subs will be used in “harsh maritime environments by leveraging commercial submersible technologies and international classing safety certification,” according to the July 13 contract announcement from the Defense Department. According to Lockheed Martin officials, they have longer endurance and can operate at greater depths than the swimmer delivery vehicles, manned flooded submersibles, that are currently used for these special operations missions. The dry submersibles will allow operators to get closer to their destinations and to be more effective when they get there, the company said.

The subs will be procured in Fiscal 2018 and 2019 and maintained through Fiscal 2021 under the contract.

As many as three DCS vehicles will be built over that time period, weighing over 30 tons apiece, Lockheed Martin said in an announcement.