Participants will be requested to perform recreational dive, which does not require particular decompression stops, at a depth of 30 meters with a 30 minutes botton time. 20 minutes after dive the same measurements as baseline will be repeated, once at rest and once after a physical effort by performing a series of 10 bending on the legs (squats). The day after dive, the participants will be interviewed by phone (FOLLOW-UP) by a physician. It will be required to report any unusual event, MDD symptom, or neurological complication.