The more difficult a wreck is to get to, the more rewarding its discovery, but also the more likely it is that you’ll run into trouble during or after your dive. Challenges become hazards quickly, and many offshore adventures are rife with risk factors that make it more likely that you’ll surface from your dive without a boat in sight.

Whether your charter sprung a leak and became a new dive site or drifted off in search of another diver here’s what you need to know to survive.

Checking your air a few times during a dive and coming up as the gauge nears zero is not dive planning. Before you hit the water this summer, brush up on the basics of gas management — this will help keep you safe and might even extend your bottom time.

Sources of contamination include hydrocarbons from compressor lubricants, carbon monoxide (CO) from engine exhaust (or overheated compressor oil) and impurities from the surrounding environment such as methane and carbon dioxide (CO₂). Dust particles in breathing gas can also be hazardous, potentially impairing respiratory function or damaging diving equipment. Excessive moisture can cause corrosion in scuba cylinders and other dive gear and may cause regulators to freeze due to adiabatic cooling (heat loss following increased gas volume).

Following training guidelines and conservatively planning our dives can reduce our risk somewhat, but learning how oxygen toxicity affects us and how we can prevent it can mean the difference between a fun dive and one that ends in injury. Push back against complacency and unquestioning acceptance of common practices—understand the effect of oxygen on your body before you plan your next dive.

IPE is the abnormal leakage of fluid from the bloodstream into the alveoli, the microscopic air sacs in the lungs. Symptoms include shortness of breath, coughing up bloody sputum, and respiratory distress. Leakage into the alveoli results in fluid buildup in the lungs, and interrupts gas exchange, similar to drowning. It is important to note that fluid resulting from IPE comes from within the body, rather than from inhalation of surrounding water.

However you define your expedition it is important to recognize that once you begin planning it you have crossed out of the realm of normal recreational or technical and entered a world that requires serious oversight, preparation, and risk mitigation. Expedition diving does not have to be technical or extreme – a recreational diving trip to a destination like Truk Lagoon could put you hours or days away from the nearest medical help and require expedition level preparations for medical treatment and evacuation.