U.S. special operators have several ways to get to work.

Green Beret teams can do free-fall jumps with oxygen from 25,000 feet, and Navy SEAL squads can spend up to eight hours in mini-submarines on combat dives.

One of the least known methods of insertion and exfiltration is the “helocast,” an airborne special-operations technique used by small commando elements to insert into semi- or non-permissive areas.

Scary but Effective

Helocasting involves commandos jumping from a helicopter into water and either swimming or using a small boat that they bring with them to get to shore.

“Helocast ops are an important insertion method in our quiver” that provides flexibility, even if it’s “not the most comfortable technique as far as insertion methods go,” a Green Beret assigned to a National Guard unit told Insider.

Through helocasting, Special Forces units “can creep up on a target without be seen” and exfiltrate very quickly if needed, the Green Beret said. “Our pilots are amazing, and they can fly right on top of the waves. They are really great because it requires a different kind of coolness to know that you have a dozen or more lives literally on your hands and still be cool about it.”

Some conventional rotary-wing units are qualified to support helocasting operations, but the Army’s 160th Special Operations Aviation Regiment, also known as the “Night Stalkers,” is the go-to choice for such missions.

The helicopters used most often are MH-60 Black Hawks, MH-47 Chinooks, and CH-53 Super Stallions, but other platforms, such as the MH-6 Little Bird and CV-22 Osprey, can be used depending on the scenario.

Despite the skill of the pilots and the quality of the platform, helocasting can be harrowing.

“It’s a pretty scary experience the first couple of times you do it. You can’t hear shit because of the helicopter rotors and you literally walk in[to] the dark, cold water of an ocean or a lake,” a Marine Raider told Insider.

“It’s all about trust. You have to trust your training, the helicopter crew, and of course your teammates. But after you’ve done it a few times it becomes easier, as with all things, but not more comfortable!” said the Marine Raider, who like the Green Beret spoke anonymously because they weren’t authorized to comment.

The helocast insertion technique is almost exclusively reserved for special-operations teams that are qualified as combat divers or combat swimmers.

That includes Navy SEALs, Marine Raiders, and Reconnaissance Marines, but also Army Green Berets assigned to a combat diving team and Air Force Pararescuemen, Combat Controllers, Tactical Air Control Party airmen, and Special Reconnaissance operators.

How Would You Like Your Duck?

There are three varieties of helocast: Rolled Duck, Soft Duck, and Hard Duck.

Rolled Duck is when the boat isn’t inflated at all, meaning the operators have to use special pumps to fully inflate it while in the water.

Soft Duck is when the boat is partially inflated, requiring the commandos to use those pumps to fully inflate it while they’re in the water.

Hard Duck is when the boat is fully inflated and good to go the moment it hits the water.

The mission and the helicopter available determine which technique is used. With larger helicopters, an MH-47 Chinook or a CH-53 Sea Stallion, it’s more likely the operators will conduct a Hard Duck.

The most commonly used boats are the trusty Zodiac, also known as Combat Rubber Raiding Craft (CRRC), and the Rigid Hull Inflatable boat (RHIBS). Which boats are chosen depends on the operation — CRRCs are smaller but RHIBS are sturdier and can operate over longer distances.

Similar to airborne operations that require jumpmasters, there must be at least one qualified cast master present during every helocast, and all the operators participating must be qualified in the insertion method.

When it is time for exfiltration, the operators can motor their boat straight into the helicopter as it hovers right on top of the water. This takes a lot of training and coordination, but it’s a quick way out of the water. Operators can also use hoists, fast ropes, and rope ladders to get to and from the helicopter.

The mission requirements, which aircraft are available, and the operational environment all influence which implements are used.

If a Green Beret combat diver team is exfiltrating from an operation in a permissive or semi-permissive area and friendly forces have air superiority, they may have more time to work with and thus decide to use a rope ladder.

Special-operations forces need to be proficient in several different insertion methods because when “the time comes for the real deal, we need to have options,” the Green Beret said. “The enemy has strong air defenses and we can’t HALO [High Altitude Low Opening parachute jump] in? We can do a helocast or an over-the-beach insertion, and the list goes on.”

This article was written by Stavros Atlamazoglou and originally published on Insider.