1. The Chesapeake Bay water is murky. Pools are clear.

There's no stripe on the bottom of the Bay so you'll have to find another way to swim straight. Try raising your head slightly every 10 (if the current is strong) or 20 strokes. You may want to practice doing this to get used to it.

2. The bay is choppy. Pools are relatively calm.

There's usually a good deal of chop in the bay especially in the channels (below the two bridge "peaks") where the current is stronger. Some people prefer to shorten their strokes and breathe higher. Learn to bi-lateral breathe so that you'll have another option if the waves are coming hard from your breathing side. The start time is set so that most people will hit slack tide at the center of the swim. However, unless you're in the fastest group, you'll probably experience one type of current at the beginning of the swim (such as ebb in the first channel) and the opposite at the end (for example, flood in the second channel). Keep in mind that wind and recent storms can have an effect on currents so try to stay positive and flexible.

3. The bay is one long, continuous swim. When pool swimming you are always no more than 25 yards from an exit.

Practice swimming long sets. Also if you're planning to eat or drink something before or during the swim, give it a trial run during a long pool workout.

4. The start of the Bay Swim is a bit frenetic. Starting at a meet is controlled and you have your own space.

The Bay Swim start features 2 waves of 300 people entering the water at virtually the same time. There's a good bit of turbulence and occasional "contact" until the swimmers fan out. If this bothers you practice riding the subway during a large downtown event or just stay to the side or rear when beginning the Bay swim.

5. The water temperature is usually 68 - 72 degrees during the Bay Swim. However, during especially cold weather, the water has been around 60 degrees. Pools are usually around 80 - 85 degrees.

The colder bay water temperature may startle you when you first plunge in (adds to the fun and excitement of joining a wave of 300 thrashing swimmers). Consider wearing a wetsuit if you're doing the Bay Swim for the first time.

6. The Bay Swim consists of continuous swimming (generally freestyle) unrelieved by chats with lane-mates or stroke sets.

Your swimming may be altered by having to swim diagonally to accommodate currents (either flood - going north or ebb - going south) or in order to deal with chop. This can cause stiffness. Try floating for a minute in a "ball" or doing breaststroke or backstroke to stretch out during the swim.