When SEALs arrive from the air, they are often going to extremely difficult-to-reach places. In this case, they may jump from a plane into the ocean with their Zodiac, parachute into the area, or use fast-rope and rappelling techniques.
When parachuting, SEALs use either static-line or free-fall techniques. Free-fall techniques include High Altitude/Low Opening (HALO) jumps and the more difficult High Altitude/High Opening (HAHO) jumps (see Navy SEALs.com: Air Equipment to learn about these types of jumps). High-altitude jumping requires oxygen and special equipment to ensure that the chute opens in the event the jumper blacks out, which is not that uncommon for high-altitude jumps. Goggles can shatter from the cold, and eyes can freeze shut, making the fall even more interesting. A device called an FF2 will automatically activate the jumper's rip cord if the chute hasn't opened at a preset altitude.
HAHO jumps, where chutes are deployed just a few seconds after the jump and SEALs form a "stack" to stay together, keep the SEALs in a tight group when they land. This is a difficult maneuver that requires a lot of training as a team. The lowest man in the formation uses a compass and landmarks to steer them to their destination.
Fast-rope and rappelling techniques require helicopters to drop SEALs by way of a rope to their location. Fast roping is a drop technique whereby a 50-to-90-foot (15-to-27-meter) rope is dropped from the helicopter, and SEALs slide down the rope using a Swiss seat harness. To brake, they apply their hands in a towel-wringing motion -- using their feet to brake would damage the rope.