Submerged structures / Lake dwellings

Submerged settlement in the Zürich Lake investigated in 1854 by Forel, Morlot, and Troyon.

The sea level in the world's oceans has remained nearly unchanged during the last 1000 years or more. One exception is the middle and north Baltic Sea, where the sea-bottom is rising. Remains of ancient dwellings or cities can be found underwater for various reasons:
A: The sea level may have risen locally, like the Swedish Vättern lake, as well as in Denmark or the La Tène and Charavines lake settlements in Switzerland.
B: The dwellings may have been built on water. Examples are the Bulverket fortification and the crannogs of Ireland and Scotland.
C: The land has sunk after seismic activity (not in northern Europe).
D: Landslides or floods may have eroded or washed buildings into the sea.

Various lakeside dwellings

Tybrind Vig, Denmark. Submerged stone-age settlement from c 5500-4000 BC, now located on ca 2 m depth. This was a large investigation project for more than 10 years involving archaeologists and volunteer scuba divers. Among the finds were log boats, tools and weapons.
Ronæs Skov, Gamborg Fjord, Denmark. Submerged stone-age settlement from c 4000 f Kr. Ref Fortidsminder og kulturhistorie (Skov- og Naturstyrelsen 1987)
La Marmotta, Italy. Submerged settlement from ca 5700 BC, abandoned ca 5200 BC. Among the finds is one 10 m long logboat.
Black Sea mesolitic settlement. Stone-age settlement found in 2000 by the Robert Ballard team, on 95 m depth off the Turkish coast. The site seems to be from before the flood, at least 7000 years old. More info.
Submerged settlement in the Bay of Wismar, Harald Lübke, Germany. Remains of dwelling from c 2000 BC, now submerged.
Dvaraka/Dwarka, India. Remains of ancient port and settlements from 1500-1400 BC and later, submerged or washed away in the Arabian Sea. Investigated since 1979. Photo courtesy National Institute of Oceanography, Goa, India. Ref British Museum Encyclopaedia of Underwater and Maritime Archaeology.
Colletière, Medieval lake settlement, France. Partly submerged after water level rise.

Pile dwellings & crannogs

Alvastra pile-dwelling, National History Museum, Sweden. Dated to c 3100 BC.
Scottish Crannog Centre
Archäologische Kulturdenkmale und Denkmalschutz am Bodensee, Helmut Schlichtherle. Maritime cultural heritage in Lake Constance, Germany/Switzerland.
Submerged settlement in the Zürich Lake, Switzerland. In 1854 the water level of the Zürich Lake was particularly low. Remains of pile dwellings were discovered and investigated. Since then, remains of hundreds of lakeside settlements have been located under water in Switzerland. The settlements were built in marshy areas during 4300 - 800 BC, and submerged much later due to raising water levels.
Pfahlbaumuseum Unteruhldingen, pile dwellings in Lake Constance (Bodensee), Germany.
La Tène, prehistoric Celtic pile dwelling, located in 1857, Switzerland. The site was submerged by later sea level rise. The original buildings may have been at the shore rather than in the water.
Bulverket fortification, Gotland, Sweden. Mysterious Medieval c 170x170 m square shaped fortification in a lake, apparently never used and abandoned shortly after construction in the 1130s AD. Several houses and three boats have been found.

Various submerged structures

Cosquer Cave, near Marseilles, France. Discovered in 1991 or '92, partially submerged cave with stone-age paintings, at least 27000 years old.
Submerged forest & possible ancient ship, the Solent, south England, forest dated to c 4300 BC
"Seahenge". Cult site in Norfolk, England dendro dated to 2049 BC. English Heritage has decided to conserve the site. Perhaps it will eventually be open to the public.
Roman underwater engineering: There are several preserved examples or Roman constructions underwater, e.g. for bridges and harbours. Wooden cofferdams were often used before the fundaments were fixed on the seabottom. This is described by Christopher Brandon in Skyllis 1/2001.
Oldest Bridge across the River Thames, Eton Rowing Lake, England, 1400-1300 BC
Bridge across Shannon, Ireland. In 804 AD a 120 m long wooden bridge was built across the Shannon River. Investigated by divers '97-98.
Tallinn Bay Marine Fortifications, Vello Mäss. Possibly 18th century AD.

Mysterious but probable natural sites

Underwater "Pyramids" at Okinawa, Japan. Unidentified (probably natural) structures.
Mysterious Deep Water Sonar Images Off Western Cuba. "Regular shapes and patterns" were recorded on the seabottom in 2000. The site is known as the "MEGA site". Is it natural or not? Since the depth is 650 metres, it is likely to be natural, but it remains to be investigated. Located in 2000 by Exploramar/ADC, the same company that discovered USS Maine. To be examined in 2002.
Taiwan. Strange structures reported in 2002.