Every event that has a swim starts in the calm waters of Lake Lloyd, within sight of the track.

The water is clean, its not so deep and a lot of people already made swim sessions on that Lake.
Please take a look at the Rowdy Gaines video about the swim course. The 3 times Olympic Gold medal winner has a lot to say about the water:

Generally, Lake Lloyd hovers between 68-72 degrees Fahrenheit. If that holds true on race day, it will be a wetsuit-legal swim. Conditions can vary, of course, and the final call will be made on race morning. We follow the USAT rulebook, which states the following:

Each age group participant shall be permitted to wear a wet suit without penalty in any event sanctioned by USA Triathlon up to and including a water temperature of 78 degrees Fahrenheit. When the water temperature is greater than 78 degrees, but less than 84 degrees Fahrenheit, age group participants may wear a wet suit at their own discretion, provided however that participants who wear a wet suit within this temperature range shall not be eligible for prizes or awards. Age group participants shall not wear wet suits in water temperatures equal to or greater than 84 degrees Fahrenheit. The wetsuit policy for elite athletes shall be determined by the USAT Athletes Advisory Council. The AAC has set the wetsuit maximum temperature for elite athletes at 68 degrees for swim distances less than 3000 meters and 71.6 degrees for distances of 3000 meters or greater. Any swimmer wearing a wetsuit with a thickness measured in any part greater than 5 millimeters shall be disqualified.

Our advice? Pack your wetsuit!

After a quick transition, you’ll enjoy an unprecedented opportunity to race a lap around Daytona International Speedway® by bike.

Next, you’ll leave the circuit via one of the north exit tunnels, a narrow tunnel with a drop and rise that will send you off onto the course like a rocket. You’ll complete a circuit on roads named after celebrated NASCAR drivers, passing alongside the famous aerospace school, just meters away from the major runways at Daytona International Airport. At the end of the course, you’ll turn back at Daytona International Speedway to prepare for your run.

Finally, it’s time for a run course like you’ve only imagined—the laps take you around the historic Daytona International Speedway® track. Maybe you won’t hit the speeds that NASCAR drivers clock, but it’s sure to be a fast run, fueled by the enthusiasm and energy of the crowds. It’s also sure to be an experience you’ll never forget!