The world's weirdest places to scuba dive

The Silfra fissure in Iceland's Thingvellier National Park is where the North American and Eurasian tectonic plates meet. The water is so clear many divers are said to lose all sense of depth and even experience vertigo. The mysterious underwater ruins of Yonaguni, Japan are estimated to be between 5,000 and 8,000 years old. Some claim the ruins to be evidence of a long lost city, while others are convinced it is a geological phenomenon. The submerged active volcano of Banua Wuhu in Indonesia seen releasing ribbons of silver bubbles of sulfur gas. The volcano's barren sulfur-covered rocks give way to coral reefs and an extraordinary display of marine life the deeper down you explore. The Museum of Underwater Modern Art in Cancun, Mexico, holds over 403 permanent life-size sculptures and is one of the largest artificial reef attractions in the world. The Neptune Memorial Reef in Miami, Florida, is an artificial reef which doubles as a cemetery. SP Mainsail diving Silfra fissure Iceland 1

Amazing Underwater River Cenote Angelita in Mexico has a little-known phenomenon that would appear to be a diver's delight: an underwater river! These photos, taken by Anatoly Beloshchin 30 meters deep inside the cave, reveals clear salty water and a murky "river." The river is actually a layer of hydrogen sulphide suspended harmlessly in the water. Avebury Avebury rivals - some would say exceeds - Stonehenge as the largest, most impressive and complex prehistoric site in Britain. Built and altered over many centuries from about 2850 BC to 2200 BC, it now appears as a huge circular bank and ditch, enclosing an area of 281 ⁄2 acres (111 ⁄2 hectares), including part of Avebury village.Within this 'henge' ditch is an inner circle of great standing stones, enclosing two more stone circles, each with a central feature. The site's present appearance owes much to the marmalade heir Alexander Keiller, who excavated and re-erected many stones during the 1930s, and whose archaeological collections are displayed in the nearby museum. Many stones had been broken or buried in medieval and later times, one crushing its destroyer as it fell. Avebury is part of a wider complex of Neolithic and Bronze Age monuments, with many other ritual sites in English Heritage care.

Malham Cove, Malhamdale, Limestone Pavements, Yorkshire Dales Malham Cove Malham Cove is a huge curving amphitheatre shaped cliff formation of limestone rock. The vertical face of the cliff is about 260 feet high. The top of the cove is a large area of deeply eroded limestone pavement, of a strange pattern rarely seen in England. The majesty of Malham Cove looks out over the Village of Malham and has been attracting visitors for centuries. Photo © Paul heaton Location: Malham Cove gr 897642 OS Map: 98, From the middle of Malham village walk up Cove Road (keep left walking up the village) for approximately 300 yards and the Cove will come into view. Access: Open all year, a good footpath leads from the road to the foot of the Cove and steps lead up to the Limestone Pavement on the top of the cove (note no parking is available at this location you must park in the Yorkshire Dales national park Authority Car Park or in the village). Size: approximately 80 metres high and 300 metres wide. Photo © Warner Bros

Isle of Skye, Scotland. Guide to Accommodation, Activities, Attractions.