If you spend much time being active around the water, you most likely have a rashguard shirt or two. The traditional rashguard does a good job at wicking away sweat but fails when really wet. In other words if you wear it in the water you end up with a shirt that is soggy, heavy, wet, and clings to your body. Not cool.
Things just changed with the Victory KoreDry clothing line (hoodies, shirts, neoprene, etc..) which acts like a hydrophobic layer repelling the water. Additionally they are produced in the US (Huntington Beach, CA) and provide UPF 50 sun protection.
You have to see the video to fully understand how different the Victory KoreDry product is compared to traditional wicking sports shirts.