The Marine Commandos, abbreviated to MARCOS and officially called the Marine Commando Force (MCF), are the special forces of the Indian Navy. The MARCOS were originally named Indian Marine Special Force, which was later changed to Marine Commando Force to impart "an element of individuality" to it, according to the Indian Navy. The abbreviation 'MARCOS' was coined afterwards. The MARCOS were founded in February 1987. MARCOS are capable of operating in all types of environments; at sea, in air and on land. The force has gradually acquired more experience and an international reputation for professionalism. The MARCOS regularly undertake specialised maritime operations in Jammu and Kashmir through the Jhelum River and Wular Lake, a 65 square kilometres (16,000 acres) freshwater lake, and conduct counter-insurgency operations in the region. All MARCOS personnel are selected from the Indian Navy when they are in their early 20s and have to go through a stringent selection process and training. The selection standards are extremely high. Training is a continuous process. American and British special forces assisted in setting up the initial training program, which now consists of a seven and a half to eight months course for new recruits. The training regimen includes airborne operations, combat diving courses, counter-terrorism, anti-hijacking, anti-piracy operations, direct action, infiltration and exfiltration tactics, special reconnaissance and unconventional warfare. Most of the training is conducted at INS Abhimanyu, which is also the home base of MARCOS. The pre-training selection process is made up of two parts. Indian Navy personnel who want to join MARCOS must undergo a three-day physical fitness and aptitude test. Within this process, 80% of the applicants are screened out. A further screening process known as 'hell's week' is similar to the United States Navy SEALs' "Hell Week".This involves a high degree of physical exercise and sleep deprivation. After this process, actual training begins. Around 80-85% of the volunteers who enroll fail to fully qualify as MARCOS. The MARCOS are trained in every kind of weapon and instruments, including knives, crossbows, sniper rifles, handguns, assault rifles, submachine guns and bare hands. Being divers, they can reach hostile shores swimming underwater.