Obviously, it’s best to learn how to swim in the relative calm of your local pool. That’s a good place to start learning three key open water swimming skills: sighting, bilateral breathing, and a “choppy-water” freestyle. For more about those skills, check out How to Swim in Open Water, Part 1.

Let’s start with the obvious: Never swim in open water by yourself. Having a fellow swimmer is one way to fulfill this most-basic safety measure, but they will be of little help if you encounter an unexpected current or creature of the deep. Better than a fellow swimmer is a friend in a kayak or a power boat. Know only land-lubbers? Have someone walk the shoreline with you, if water and weather conditions allow it. If disaster strikes, this person can go for help.

Swiftly moving water can pull you astray, potentially miles off-shore, off-target or even underwater. In many popular open water swim locations, currents are infamous for their strength and speed. In other places, you may need to do some asking around to find out about water conditions, which can change hourly.

Most pools are between 79 and 85 degrees. Most bodies of water are not that warm. Thanks to water’s ability to conduct heat and the fact that your body is contacting the water over the entire surface area of your body, every one degree change in water temperature FEELS like a 10-degree change in temperature. Water that is 70 degrees Fahrenheit doesn’t sound that cold (heck, your thermostat is set at 68), but it really is. If you are not going to be in cold water that long, you might be okay without a wetsuit. Just beware that you are at risk for suffering from hypothermia, and should know the symptoms. Of course, there are many other health risks associated with swimming in super-cold water, and you should know those too before you do something silly like swim to Antarctica without a wetsuit. (No, really, Lynne Cox is famous for this feat. Her book is an inspiring read.)

On the other hand, if the water is really hot, and you plan to swim for a long time, dehydration is a risk. Remember that friend you have paddling in a kayak next to you? Have them hand you a water bottle from time to time. Not sure how to drink and eat while you are swimming in the open ocean? Check out some video of Olympic open water swimmers going through the “feed zones” of the first-ever open water race in the 2008 Beijing Olympic Games.

Many other weather factors can affect conditions in the water. Wind can create “chop,” or surface waves. Stormwater runoff can alter temperature and water clarity. Warm springtime weather can cause cold, deep, fast-moving water even into the summer months. Find out how local weather conditions are affecting water conditions where you want to swim.

Find out what creatures you are likely (or even unlikely) to encounter on your swim. Is the bay home to any sharks? (Some sharks are completely harmless to humans.) Are there jellyfish or nettles? Think little too: are there unacceptable levels of bacteria? Many beaches are actually closed to swimming after rainstorms because of dangerous levels of bacteria that arrive with the stormwater runoff. Broken shells and coral? What about territorial sea lions? Might you encounter thousands of migratory geese at your exit point? Make a mental plan for what you can do if you encounter any of the local wildlife.

Where are you planning to go on your swim? Is it point-to-point or an out-and-back adventure? Are you planning to swim back and forth many times over a shorter distance? Whatever your answer, have a plan and know the route. Most importantly, familiarize yourself not only with water conditions, but also with the shoreline. Particularly if you are swimming point-to-point, check the exit point, and make sure you can actually get out of the water there! It sounds silly, but crashing surf, sharp rocks or coral, slippery sea slime, cliffs, thigh-deep mud, or even thick wetland vegetation could make your intended exit-point impossible, or far more dangerous than it ought to be.

Before you set off swimming, have a plan for exiting the water if conditions (or you) deteriorate. Expect that unexpected things may happen. Maybe your breakfast will not power you for as long as you had imagined. Maybe a sudden squall is headed your way. Maybe you will encounter a flotilla of garbage that arrived with the runoff from last-night’s rain storm. (Swimming in open water the day after a rain storm is not necessarily a great idea.) No matter what unexpected thing occurs, your plan B will help keep you safe. This is where the friend in a power boat can be handy. Just climb in the boat if conditions are that bad, and you’ll be on your way to solid ground in no time. The closer you stay to shore, the more options you will have, especially if the shore is exit-able for the entire length of your swim.

At some open water swimming areas, local jurisdictions have lifeguards on duty. Tell the lifeguards what you are doing. Not only may they be able to come to your rescue if you get caught in a current, but you’ll also ensure that they won’t come racing out to “save” you when they see you swimming somewhere they wouldn’t expect you to be. The added bonus of checking in with the lifeguards is that they will have up-to-date information on weather and currents.

You’ve been practicing your skills in the local pool and you’re ready to get beyond comfort of the black line. Even if you are feeling unafraid of the unpredictability of open water, take it easy on your first swim. Gain experience with some easy swims (back-and-forth along a lifeguarded beach, for example), so that when you encounter your first open-water problem/challenge, the stakes aren’t life-threateningly high. If you are feeling nervous and scared about your first open water foray, try to find a place with calm water where you can swim parallel to shore. Ideally, this place will have water that is shallow enough for you to stand, should you feel the need to stop swimming.