Try to wear light clothing; this will make it easier to swim if you are washed in. Jumpers and thick cotton clothing become very heavy when wet, impeding swimming and can be difficult to take off quickly.
For warm weather:
Because of the harmful effects of the sun and its ability to cause skin cancer, it is a good idea to wear a high SPF sunscreen as well as a hat and protective clothing with long sleeves and light colours to reflect sunlight. Because UV rays from sunlight can harm your eyes, it is a good idea to wear sunglasses. In addition to sun protection, polarized sunglasses can reduce the glare from sunlight reflecting off the water’s surface, allowing you to see beneath the surface of the water to spot fish, even on sunny days.
For cold weather:
In cold weather it is very easy to lose body heat. Long, warm clothes that cover as much body surface as possible and beanies or hats can help retain this body heat. In cold weather gloves can also help to keep you warm and you can purchase lightweight rubber gloves or finger-less gloves that allow you to handle tackle and stay warm. If rain is likely it is important to bring waterproof (not just water resistant) gear such as a jacket with a hood and/or waterproof pants.