The United States Navy's Sea, Air and Land Teams, commonly known as the Navy SEALs, are the U.S. Navy's principal special operations force and a part of the Naval Special Warfare Command and United States Special Operations Command. One of the SEALs' primary functions is to conduct small-unit maritime military operations which originate from, and return to a river, ocean, swamp, delta, or coastline. SEALs can negotiate shallow water areas such as the Persian Gulf coastline, where large ships and submarines are limited due to depth. The Navy SEALs are trained to operate in all environments (Sea, Air, and Land) for which they are named. SEALs are also prepared to operate in a variety of climates, such as desert, arctic, and jungle.