The famous Navy SEALs unit is a special operations group trained to carry out missions on land and in the air, but SEALs are best known for their underwater work. Payment explains their history, their missions–which often involve scuba diving and underwater demolitions–and what it takes to become a SEAL. Readers get a sense of the intense and exhausting work involved in being a SEAL, as well as the resources and methods used to successfully complete dangerous missions.