Have to love Wikipedia, sometimes!!
The JIM suit is an atmospheric diving suit (ADS), which is designed to maintain an interior pressure of one atmosphere despite exterior pressures, eliminating the majority of physiological dangers associated with deep diving. Because there is no need for special gas mixtures, nor is there danger of nitrogen narcosis or decompression sickness (the 'bends'); the occupant does not need to decompress when returning to the surface. It was invented in 1969 by Mike Humphrey and Mike Borrow, partners in the English firm Underwater Marine Equipment Ltd (UMEL), assisted by Joseph Salim Peress, whose Tritonia diving suit acted as their main inspiration. The suit was named after Jim Jarrett, Peress' chief diver.