Sun protection is a good reason to wear a hood. The loose fit allows for good ventilation. In hot weather you can stay cool by keeping the hood wet.
Unlike a sun hat, a hood doesn't come off in the heat of the action, but stays put when you jump around in the water.
For more relaxed activities, or simply when used as a sun shade, you may want to wear a loose fitting hood as a comfortable cover with good ventilation.
Some people prefer the loose fit over the tight Lycra hoods. You can swim faster in a hooded speed suit, but we've found hooded clothes are the most comfortable and practical sun protection for water sports. After swimming they dry quickly in the breeze, no need to change clothes.
A large hood has good ventilation and can cover your face, but best of all you can play around with it.