The unidentified jumper stood poised on the edge of the cliff in Penzance, Cornwall, before hurling himself into the air.
With arms flailing, he spent around 2.5 seconds in freefall before crashing into the sea below.
Splashdown: This sequence of 11 pictures shows the trajectory of the jumper's freefall and the splash he made when hitting the water
The sea is believed to be about 20ft deep in the spot where he landed.
Photographer Alastair Sopp caught the leap on camera in a sequence of 11 images.
Alistair said he spoke to the 'tombstoner' shortly after he made his death-defying jump.
He explained he'd made the dive after studying tide and weather charts for weeks but it still took a while to pluck up the courage.
'It was a breathtaking moment. I couldn't believe he jumped from so high up.
'I went and saw him down below and he said a lot of planning had gone into it, visiting on different tides, waiting for weather, and diving down to check depth.
Dicing with death: This tombstoner launched himself of a 100ft cliff in a death-defying leap, before landing in the sea, believed to be about 20ft deep
With his arms outstretched, the tombstoner fell for about 2.5 seconds before hitting the water
Despite repeated calls for young people to stop throwing themselves off cliffs and piers into Britain's waters, the message clearly had not filtered through to this daredevil.
Each year coastguards and ambulance services are called to deal with horrific injuries including paralysis and broken necks, as people leap into the water unaware of the risks.
Many hurl themselves into the sea not realising the dangers which lurk below the surface, such as rocks and debris, while others simply jump into shallow water, leaving themselves at risk of potentially fatal and brain spinal injuries.
The first known tombstoning fatality in the UK was Stephen Royston, 24, who jumped 100ft (35m) into a water-filled quarry at Kit Hill, Cornwall, in 2003.
In August 2007 16-year-old Sam Boyd died after leaping into Minehead Harbour in Somerset where he was then washed out to sea.
Father-of-six Delwyn Jones, 46, was killed two months earlier when he jumped 30ft (9.1m) at low tide in Torbay, Devon.
A year later in May Steven Andrews broke his neck and was paralysed for life after falling 20ft nearby Whitsand Bay.