Diving without oxygen tanks requires you to enact some very weird and very strange and not all that well understood physiological feats just to stay alive.
Scientific fieldwork that happens underground and underwater in spectacular but dangerous caves opens a window on a largely unknown world.
The choke factor is visible in tournament-style athletics competitions, and should teach managers about incentives.
The possible culprits are: a sudden algae bloom; a change in pool alkalinity; or a chemical reaction in the water. How do these cause a change in the colour of the water?
Africa has a number of excellent scuba diving sites, but these must be maintained sustainably to keep attracting different divers.
Diving in many parts of Indonesia, Thailand and Malaysia now costs a little more than it used to – but you might be happy to discover why.