Choose a quiet day. You can stay in a swimsuit. Just observe how unremarkable nudity is. Notice the range of bodies. Notice that no one is staring.
Look for a "non-landed" (traveling) club in your area. They often hold swims or yoga sessions. These are highly regulated, non-sexual, and beginner-friendly.
The biggest misconception about naturism (or nudism) is that it is inherently sexual. In reality, the naturist philosophy is built on the foundation of —the idea that the body is just a body.