Abstract: A waterproof housing that encloses a hand-held magnetometer for underwater use and includes a first portion open at one end and connected to a second portion with one end open and accessible through the first portion and terminating at a closed end. The magnetometer has first and second housings and is inserted into the first portion open end so that the second housing is received into the second portion and the first housing is received into the first portion. A base seal is inserted into the first portion open end to provide a fully functional magnetometer protected from water incursion at depth.