Scientists studying Amazon river dolphins in Brazil have observed males spraying urine into the air, a ritual for communication.

Like salmon, trout are a type of fish who spend most of their lives at sea but swim up rivers to lay their eggs. Research your local area and find out where the nearest river is to your home.

Unless you’re planning on swimming the Channel under traditional rules – which which only allow you a simple swimsuit or pair of trunks, a swim cap and a pair of goggles – then there’s no reason not ...