The company that helped map the wreck of the Andrea Doria is moving forward with the construction of a submersible craft that can go much, much deeper – 4,000 meters (13,123 feet) deep, or two and a half miles below the ocean surface.

OceanGate announced on Thursday that it has officially begun construction of the five-person Cyclops 2 submersible. The company, based in Everett, Wash., has been working on the design and engineering for the 22-foot-long craft in cooperation with the University of Washington’s Applied Physics Lab since 2013.

Over the past year, OceanGate has been pressure-testing a one-third-scale model of Cyclops 2 in preparation for moving ahead with the full-scale vehicle.

“Construction of Cyclops 2 is a significant milestone in human exploration of the ocean,” OceanGate CEO Stockton Rush said in a news release. “When completed, it will be the only privately owned submersible in the world that can take five people to these depths.”

Some crew-capable submersibles have gone deeper. For example, in 2012, filmmaker James Cameron went nearly 11,000 meters (36,000 feet) deep in the Deepsea Challenger submersible, with Seattle billionaire Paul Allen providing an assist. But that craft was built to hold only one person. It’s the roomy, five-person capacity that makes the Cyclops 2 attractive for OceanGate.

OceanGate took its first step toward building Cyclops 2 when it ordered two titanium hemispheres and two titanium-to-carbon-fiber interface rings from Titanium Fabrication Corp., or Ti Fab. OceanGate also put in an order with Spencer Composites Corp. for the 100-inch-long, 56-inch-wide carbon-fiber main cylinder.

Fabrication of those components should begin immediately, with delivery scheduled for next spring. OceanGate will mate the hemispheres to each end of the main cylinder, test the hull, then outfit the craft with electronics, navigation devices and the life support system. The first in-water dives for Cyclops 2 are planned for late 2017.

Many of the systems on Cyclops 2 will be identical to those used on OceanGate’s Cyclops 1, which is designed to go as deep as 500 meters (1,640 feet, or a third of a mile).

In June, OceanGate used Cyclops 1 to survey the remains of the Andrea Doria, an Italian-flagged passenger liner that sank in the Atlantic near Nantucket Island in 1956 after colliding with another passenger vessel.

The shipwreck is sitting only 240 feet beneath the surface, but the surroundings are notoriously difficult for divers. The survey work is due to continue next year, and is expected to result in a virtual 3-D model of the decaying wreck and the surrounding debris field. That model could be put to use in an upcoming documentary, and also help divers avoid hazards in the future.

Since its founding in 2009, OceanGate’s submersibles have conducted more than 150 dives in the Pacific, the Atlantic and the Gulf of Mexico to document shipwreck sites, conduct underwater surveys of oil and gas operations, observe and record marine life and underwater habitats, and recover historical artifacts.