To dive safely, it is suggested that the diver have a working knowledge of waves, tides, currents, and water quality. Lack of understanding and respect for ocean currents and surf can be of serious consequence to the diver. This paper on the diving environment is designed to provide the diver with a general understanding of the physical characteristics common to lakes and oceans. The descriptions of diving techniques are included to give the diver a better understanding of how to safely handle himself/herself under various conditions. The discussions include: (1) waves at sea; (2) waves in shallow water; (3) surf; (4) currents; (5) sandy beach entry; (6) rocky shore entry; (7) tides and tidal currents; (8) wind currents; (9) seiches; (10) diving in currents; and (11) weather. The document concludes that good physical condition, basic knowledge, common sense, and good judgment can be very important for safe underwater exploration. (CW)