Vai Lahi

{{Short description|Volcanic crater lake on Niuafoʻou, Tonga}} {{Infobox body of water | name = Vai Lahi | native_name = | native_name_lang = | other_name =  | image = | alt = | caption = | image_bathymetry = | alt_bathymetry = | caption_bathymetry =  | location = [[Tonga]]n island of [[Niuafo'ou|Niuafo{{okina}}ou]] | group = | coordinates = {{coord|15.605|S|175.64|W|type:isle_region:TO|display=inline,title}} | type = [[Volcanic crater lake]] | etymology = | part_of = | inflow = | rivers = | outflow = | oceans = | catchment =  | basin_countries = | agency = | designation = | date-built =  | engineer = | date-flooded =  | length = {{convert|4.5|km|abbr=on}} | width = {{convert|4|km|abbr=on}} | area = {{convert|13.6|km2|abbr=on}} | depth =  | max-depth = {{convert|121|m|abbr=on}} | volume = {{convert|1|km3|abbr=on}} approx | residence_time = | salinity = | shore =  | elevation =  | temperature_high =  | temperature_low =  | frozen = | islands = | islands_category = | sections = | trenches = | benches = | cities =  | pushpin_map = Tonga | pushpin_label_position = | pushpin_map_alt = Location of the lake in Tonga. | pushpin_map_caption =  | website = | reference = }} [[File:Niuafoʻou.gif|thumb|right|300px|Map of Niuafo{{okina}}ou, showing Lake Vai Lahi]] '''Vai Lahi''' (''[[Tongan language|Tongan]]: Big water'') is the central [[Volcanic crater lake|crater lake]] of the [[Tonga]]n island of [[Niuafo'ou|Niuafo{{okina}}ou]]. The island is the most northerly island of Tonga, is the most northerly island in the kingdom of Tonga, and is located some 570 km north of the kingdom's main island, in addition to that [[Tongatapu]]. Niuafo{{okina}}ou is annular in shape, the rim of an active volcano. The island ring encloses two large lakes, Vai Lahi and the much smaller Vai Si{{okina}}i (also known as Vai Mata{{okina}}aho), plus some eight much smaller ponds.<ref name="LOE">Kempe, S., and Kasmierczak, J., "Terrestrial analogues for early planetary oceans - 5. The caldera lakes of Niuafo{{okina}}ou", in Hanslmeier, A., Kempe, S., and Seckbac, J., (eds.) (2012) ''[https://books.google.com/books?id=9xxdhs29fnIC&dq=Vai+Lahi&pg=PA205 Life on Earth and other Planetary Bodies]'' New York: Dordrecht.</ref>

Vai Lahi is a roughly circular crater lake with a diameter of 5 kilometres. Its surface, reported as 23 metres above sea level in 1935, is now believed to be close to sea level. The same survey which reported these new findings also discovered that the depth of the lake is considerably greater than previously thought; long thought to reach a maximum of 84 metres, it has recently been found to be 121 metres deep at its deepest point.<ref name="LOE"/> The lake has a perimeter of 15.5 kilometres, and a surface area of {{convert|13.6|km2|sqmi|abbr=on}}. Vai Lahi has a volume of almost one cubic kilometre.<ref name="LOE"/> The waters of the lake are warm and mildly [[alkali]]ne.

The lake contains three islands and a submerged island that appears when the water level drops. The largest of these islands is the central Motu Lahi (''Big island''). The other islands are Motu Molemole, Motu Si{{okina}}i, and the ephemeral Motu {{okina}}A{{okina}}Ali.

Niuafo{{okina}}ou has been sporadically active throughout recorded history, with six eruptions during the twentieth century. The most violent of these, in 1946, resulted in the evacuation of the island (the first groups of inhabitants were allowed to return to the island in 1958).

==References== {{reflist}}

==External links== *[https://www.panoramio.com/photo/1840658 Image of Vai Lahi]

[[Category:Lakes of Tonga]] [[Category:Volcanic crater lakes]] [[Category:Niuas]]