Blake had often been around water, he had learned to swim at a very young age, but had also seen several of his friends in childhood come close to a near drowning ... water was a force to be reckoned with.

"Well I think the most obvious is the possbility of drowning. Not knowing how to swim and being around water is rather dangerous." Blake's answering were almost always of the mundane rather than magical answer, you'd think after starting his 3rd year he'd have more magical answers.