Each year, 15 to 20 visitor rescues are directly associated with unprepared victims finding themselves in the water either on purpose (swimming, boating, rafting) or accidentally (falling while hiking, crossing streams, scrambling on rocks). As a matter of fact, water-related accidents are the second most common cause of death in the park!
Often, people do not experience fear when standing next to water in the same way that they would if they were standing on the edge of a precipitous cliff. However, intentional or unintentional entrance into the water can be as dangerous as falling off a cliff.
Follow posted signs. If a sign says "NO SWIMMING," don't swim or wade! Hazards are often invisible on the surface and calm water may hide dangerous conditions. Areas are closed to swimming and wading in places (like Emerald Pool, above Vernal Fall) where multiple incidents occur each year.
Confidence in a familiar environment leads to danger in an unfamiliar one. For example, a strong ocean swimmer with no knowledge of swiftwater hazards might assume that their swimming skill is all they need. It’s not!
When rafting or kayaking, wear the required personal protective equipment (PPE): A life-jacket (personal floatation device or PFD) appropriate to the activity is the absolute minimum. Other equipment may include helmet, wetsuit, whistle, and knife.
Do not leave children unattended. They often don’t recognize danger. Young children can drown in relatively shallow water.
Always wear sturdy shoes. There are sharp objects in the water that will cut bare feet.
Alcohol and river activities do not mix. Approximately half of all boating and swimming deaths involve alcohol.
If you fall in, use the defensive position: on your back, feet pointing downstream and on the surface.
Do not swim or boat alone.
Be aware that mountain water is extremely cold, despite hot air temperatures. Strong swimmers may quickly become too weak from hypothermia to swim. Even professional swiftwater rescuers wearing layers of insulation sometimes struggle to stay warm!
Even a slow current will take you where you may not want to go. Remember, "slow" is a relative term in the mountains... you probably won't be able to swim to shore or away from a hazard faster than the current is taking you towards it.
Watch for water hazards, like submerged tree branches, abandoned cables, or narrow gaps between rocks, which can trap you or part of you underwater, causing hypothermia and even death. The pressure from even a "slow" current can be enough to immobilize you against an obstacle and keep you submerged.