For stand up paddleboarding, common practise is to be attached to your board with a leash at all times. The board is your buoyancy aid, as with surfing. If you find yourself in the water, then you are still attached to a giant floating object, which will be by your side ready for you to hop back onto.

Buoyancy aids are optional for over 18s when out on an SUP but we do ask people who are not confident swimmers to wear one for extra water confidence.