Nothing beats a good day at the lake, where you can enjoy the invigorating chill of cold fresh water and dry off with trees and a blue sky as a backdrop.

Lakes’ dark, shimmering waters hold a special appeal for many of us. They also pose special hazards for swimmers and boaters, from drowning risks to bacterial contamination.

Before you jump in (or motor on), heed a few key pieces of advice.

1. Wear a vest in the boat (and make the kids wear one, too). If you think you’re too cool for a life vest, ask yourself if staying alive is worth any perceived indignity or inconvenience.

Recently a 60-year-old man launched his boat on a lake west of Minneapolis to hunt ducks. When he failed to return, authorities went out to search and found him unconscious in the water. The hunter, who had apparently fallen from his boat, was rushed to a nearby medical center, where he was pronounced dead.

A similar accident played out in central Minnesota. A man and two 15-year-old sons set out one early morning to hunt. When they didn’t return, rescuers began searching the lake. They found the submerged boat near shore and soon found all three hunters — cold and wet but safely on shore.

Two incidents, both on lakes, both involving boats, but with very different endings. What was the difference? The first victim didn’t wear a life vest. The hunters in the second accident all did.

“Most people who drown, who die from a boating accident, are not wearing their life jackets,” says Debbie Munson Badini, boat and water safety education coordinator for the Minnesota Department of Natural Resources. Across the nation, she says, 84 percent of people who die in boating accidents fail to wear these simple but lifesaving devices. “We recommend that any boaters wear their life jackets.”

Another good reason for life vests: Compared with swimming pools or even the ocean, lakes are often murky. It may be difficult to spot (and therefore rescue) a companion who has fallen in the water.

Look for a life jacket approved by the U.S. Coast Guard. (No, foam toys and inflatable water wings are not life-saving devices and can’t take the place of a life vest.) Wearing life jackets might prevent as many as half of all boating fatalities, according to the Centers for Disease Control and Prevention. Munson Badini puts the number even higher, perhaps cutting the death rate in Minnesota alone by more than two-thirds.

Related:  Safe — and Unsafe — Flotation Devices for Kids

And life jackets are not just reserved for boats. If you’re water-skiing, water-boarding or knee-boarding, use a life jacket as well. If your kids are playing in a lake or along a dock or shore, put them in life jackets, too.

2. Swim with a buddy. “Number one for swimming is you should never swim alone — ever,” says Munson Badini. “People swim alone and they get themselves into trouble, and there’s no one there to help them.”

3. Don’t drink alcohol, especially if you plan to swim or if you’re supervising kids. Says Munson Badini, “You start drinking, you lose a little bit of your physical abilities, your judgment. You aren’t going to be able to last as long if you fall in the water and try to swim, especially in cold water. Drinking and boating and drinking and swimming do not mix.”

4. Avoid bacteria and algae. Some lakes may be contaminated by bacteria or harmful algae blooms. If signs advise no swimming due to water contamination, enough said. To avoid getting sick, even if swimming isn’t prohibited, stay out of the water if you have a cut or other open wound, and try not to get lake water in your mouth. It’s also a good idea to shower after swimming in a lake.

Very rarely, an ameba called Naegleria fowleri makes people sick when it goes up their nose and travels to the brain. Infection with Naegleria fowleri is usually fatal. According to the CDC the risk is higher in warmer, southern lakes, but infections have occurred as far north as Minnesota. While the risk is already extremely low, you can lower it further by preventing lake water from going up your nose. The CDC recommends holding your nose shut, using a nose clip or keeping your head above water.

5. Look before you leap. You can’t see into lake water, so you can’t know what’s beneath the surface or what underwater hazards, such as rocks or logs, may be lurking. Don’t dive head first, or even jump from any significant height, into unfamiliar water.

6. Teach the kids to swim. It’s a no-brainer: Formal swimming lessons reduce the risk of drowning among young children, according to the CDC. And make sure you know how to swim. (Swimming classes are available for adults, too.) Lakes may seem like safe places to swim compared to the ocean, but people can and do drown in them.

Rip currents — narrow, high-speed currents heading away from shore — are most common in the ocean, but they can also occur on large lakes with big waves and pounding surf. If you’re caught in a rip current, swim parallel to the shore until you reach slack water and can swim in.

7. Watch the little ones. Drowning often isn’t a drawn-out, dramatic ordeal. It can happen silently and quickly. Be close enough to reach a child at all times, and don’t engage in distractions such as reading or checking your phone.

8. Take a boating safety course. Operator error and lack of training contribute to boating accidents. According to a CDC report, 77 percent of deaths occurred on vessels whose operator had not received boating safety instructions.

9. Learn CPR. According to federal health agencies, CPR saves lives, and the sooner it begins the better. Says Munson Badini, “Anybody who is going to be spending a lot of time on the water should be taking swimming classes, a basic life-saving course where you’re going to learn water rescue and CPR. Those are all things that are going to help you when you get into an emergency situation.”

Related: How — and When — to Perform CPR

10. Rescue right. If someone falls in, throw them a floatable object or reach to them with something they can grab, like a towel or paddle. In Minnesota recently, a 60-year-old man jumped off his paddle boat to rescue two kids who had slipped from an inner tube he was towing. The children, both wearing life vests, survived, but the man drowned. Says Munson Badini, “The instinct of course, especially if it’s a child, is to go in after them.” But the chaos of an impromptu rescue and a desperate, flailing victim endanger your own life unless you are trained in rescue techniques.

11. Watch the weather. Keep an eye on the weather while boating to avoid high winds and waves. Head in at the first signs of thunder or lightning, whether in a boat or on shore.

12. Cover up, use sunscreen and stay hydrated. Limit your time in the sun to keep from burning and to avoid heat exhaustion and heat stroke, and be sure to drink plenty of water. Be aware of warning signs and symptoms of heat illnesses, such as heavy sweating, weakness, cold or clammy skin (or hot, red skin), nausea, dizziness, confusion and a fast pulse. If you or someone else experiences these, get to a cool, shady spot and seek medical help.

Related: 7 Signs You Need a Drink of Water

Greg Breining is a Minnesota-based journalist who writes about science, travel and nature for national and regional magazines, including Audubon and National Geographic Traveler. His books about the natural world include Wild Shore and Paddle North.