As of 2014, the deepest a submarine has gone is 14,760 feet, which was by a deep-sea submarine named Alvin. Alvin will have modifications made, contingent on funding, so that it can reach depths of 21,325 feet while still carrying three people.
Deep-sea submarines go much deeper than submarines in service with the Navy. Although the Navy classifies its exact depths, it revealed that a Naval submarine will submerge greater than 800 feet, but less than deep-sea submarines. Scientists designed deep-sea submarines to explore the bottom of the ocean. Susan Humphris, leader of the project upgrading Alvin, said that current depths reach about two-thirds of the ocean but, with Alvin's upgrade, they will be able to reach 98 percent of the ocean.