There are few things more pleasant in life than a refreshing dip in the ocean on a hot summer’s day. But lurking beneath the waves are millions of not-so-friendly sea-dwellers – and they exist in every continent, from Oceania to Asia and Central America. Somehow, we’ve managed to rank the top 30, in order of their deadliness to humans.

Click through this gallery to discover the world's most dangerous sea creatures (some more surprising than others)...