Coming from the entrance of Tank Cave, this is the point at which the tunnels split. The A Tunnel leads off to the left and the C Tunnel continues straight ahead.
Tank Cave - F Tunnel
Deep in the bowels of Australia's Tank Cave is a beautiful long straight tunnel called F Tunnel, stretching for a couple of hundred metres.
Tank Cave - C Tunnel
As tunnels fan out from the Tank Cave entrance they are named off by letter: A, B, C, D etc.
Tank Cave at D2
This floor to ceiling feature leftover from when water eroded out the passages of the cave that cave divers now swim through is a favourite of mine.
Tank Cave ice chamber
Local cave divers will know this room in Australia's Tank Cave by the inspirational name "90 Metre Room". I like to think of it as an ice chamber with a molten ceiling. It definitely feels icy on a smoking hot Australian summer's day!
Stalactites are icicle-like rock formations that hang from the ceilings of caves. They're one of the delicate formations that we need to dive most carefully around when cave diving.
Bringing light to the dark
Away from the cavern zone, underwater caves exist in perpetual darkness, lit up for mere seconds as cave divers pass through.
A slab of rock that was once part of the ceiling lies like a giant altar on the road through Mexican cave system Sac Actun.
The world explored by cave divers
In the subterranean passages of Mexico's Yucatan Peninsula is an underwater world enjoyed by cave divers.