A recent tragedy on the Potomac River left a father and son dead after swimming off a boat. Taking key steps could keep you safe while swimming at anchor. Photo: Capt. Jen Fritz

VIDEO: Avoid Danger when Swimming off the Boat

It’s a blissful summer pastime for many on the Chesapeake Bay: take the boat out for a cruise, drop anchor in a river or cove, and go for a swim off the stern.

But swimming off the boat is far riskier than many people realize—and there are some key safety precautions that could make the difference between a fun afternoon and an awful outcome. A tragic case on the Potomac River earlier this month underscores how quickly a simple swim can become dangerous.

Cheryl Costello talks to the two boating instructors that saved a life in the Potomac incident, who say the experience has changed the way they boat. Watch below: