A public pool is an ideal setting to learn how to swim, because so many variables are well controlled and support and supervision are generally close at hand.  And yet, even when swimming proficiency is well established, pool swimmers may find themselves surprisingly anxious when starting to swim in an open water setting–many new variables become evident that they have no experience with.  Taken together, these variables can feel overwhelming, so it is important for swimmers new to open water to re-establish their swimming confidence with repeated exposure to this new milieu, and preferably in a variety of safe conditions and locations.  Here are the most common variables that new swimmers have to confront and overcome:

1. Open water is usually colder than water in a public pool, often by 10°C or more.
2. Open water is usually choppier and wavier and may include swells, which are variable and unpredictable, and affected by winds; since weather affects wind and wave conditions and can change quickly, knowing the forecast becomes an important consideration when going for a swim.
3. The water is usually darker and less clear, and it may have a taste, such as of salt or other minerals, or perhaps pollutants (such as petroleum products from boats).
4. The bottom is not well seen; there may be underwater hazards (e.g., rocks, coral, or deadwood); and the water’s depth is often unknown.
5. There may be debris in the water, whether household garbage, leaves, dead fish, driftwood, oil slicks or even sewage.
6. There may be various life forms, such as seaweed, milfoil, insects, fish, otters, turtles, seals, dolphins, or diving birds.
7. There may be things on the water to look out for, such as watercraft — power boats, sail/kite-boarders, surfers, canoes,  or kayaks; water-skiers or fishermen; docks or buoys and their underwater attachments; and of course, other swimmers.
8. There is no solid dark line below you, or lane ropes beside you, to help keep you swimming straight.
9. You will need to learn the skill of “sighting” to swim straight, and to become aware of sighting markers (e.g., trees, buoys, mountains, or buildings).
10. Self-reliance is increasingly necessary, as the usual safety net that include lifeguards is not usually near you or even present should you have any problems.
11. Distances are harder to judge given the expansiveness of open water; distances are often more intimidating to look at than the short length of a pool.
12. Currents, undertows, and tides are not usually visible and not easily felt, but are significant risk variables that can adversely affect your swim–you must consider these before getting into the water.
13. New equipment variables are added to open water swimming–particularly wearing a wetsuit– it must be well-fitting around the neck, and not restrict shoulder and chest movements, which can affect stroke mechanics and breathing, respectively.
14. Your visibility to others will be more limited, especially those in boats not expecting to see a swimmer in open water, therefore you need to be proactive to protect yourself, with the use of a brightly colored swim cap and even a personal swim buoy.
15. Swimming in open water with others will require developing comfort and tolerance to frequent body contact, especially in mass start swim events.
16. You will need discipline to objectively say no to swimming in open water if your judgment of the risks (such as weather changes) exceeds your abilities to cope with them

The only way to get comfortable with these variables is to take them on–regularly–several times a week if possible, to develop your tolerance and your confidence in open water.