Diving teams from the Port of Long Beach and U.S. Navy conducted their first-ever joint underwater emergency salvage-and-recovery exercises in harbor waters this week.

The three-day exercises are wrapping up today as the crews will practice repairing underwater structures off Pier T, prepping for potential infrastructure damages that could occur in the event of a catastrophic event such as an earthquake.

The exercise, called “Patriot Partner,” sunk a container to simulate a submerged vessel, and made underwater repairs in the event of an obstruction or pier collapse. Long Beach is the only port in the country with an underwater salvage and-recovery diving team, and only the U.S. Navy in San Diego has such capabilities.

The simulations were conducted to ensure that the port would be equipped to handle a devastating event, in order to keep port facilities open. The closure of the ports of Long Beach and Los Angeles could do severe economic harm to the entire nation.

Photographer Nate Toering braved the high seas to capture these images of the divers preparing for the demonstration.