By WIL LONGBOTTOM
Sub zero: A diver swims through a tunnel carved into the underside of a glacier in Sassolo Lake, Switzerland, by changing water temperatures
These breath-taking images were taken of an underwater maze inside a glacier by an intrepid explorer.
Photographer Franco Banfi braved sub-zero temperatures to dive under thick ice and capture these remarkable pictures at Sassolo Lake, Switzerland, at considerable risk to his life.
The glaciers create extraordinary underwater caves and passages due to changes in temperature between the summer and winter months.
Underwater maze: Photographer Franco Banfi dives underneath glaciers to explore the tunnels and caverns left in the ice
And the make the perfect project for Mr Banfi, 52, who explores even the smallest passages within the icy maze.
He said: 'In temperatures of just 2-3C or below it can be dangerous if you don't know the place and if you don't have experience in an ice environment.
'It gets quite dark depending on how much ice there is above your head at the surface - so in some places with thicker ice it gets dangerously dark.
Dangerous hobby: It can be extremely dark underneath the glaciers, depending on how thick the ice is, and most divers use a rope to find their way out again
'The underwater tunnels form when ice compacts in the winter months and in spring when it starts melting creating cracks and tunnels like in these pictures.
'I do risk my life but I have years of experience includign around 100 dives under the ice. It's the passion which drives me to get the perfect picture.'