The giant caldera of Ambrym Volcano has several craters. Up to recent time here were located two of the few lava lakes of the world – one in Mbwelesu Crater (known as Marum Crater) and another in the nearby Benbow Crater.

Giant volcano

The whole island of Ambrym has been shaped by the enormous basaltic Ambrym volcano. Sometimes around 190 AD (or somewhat later… or before this… exact date is not known) here happened a giant volcanic eruption which created the present-day Ambrym caldera which is some 12 by 8 km large.

Later in this caldera rose several craters – two larger ones (Benbow and Marum) and three smaller ones.

Ambrym is one of the world’s most active volcanoes up to this day. It’s eruptions often are disastrous and local people from time to time (e.g. in December 1913) are forced to flee from the island.

Plumes of ash from Benbow and Mbwelesu craters, December 2013
Plumes of ash from Benbow and Mbwelesu craters, December 2013. / Stuart Rankin, Flickr / CC BY-NC 2.0

According to a local legend, one of the villages has a special power over the volcano. They have magical stones hidden in the ground – these stones can cause the eruption.

Lava lake in Mbwelesu Crater

The research history of Ambrym volcano is fairly short – only in the late 19th century, it was first climbed. Several times there have been observed lava lakes. For several decades from the 1990ies until December 2018, there existed two lava lakes – one in Benbow Crater and one in a smaller side crater of Marum – Mbwelesu Crater.

In August 2018 there were even three lava lakes – a third one appeared in Niri Mbwelesu crater around January 2018.

The lava lake in Mbwelesu crater could be observed right from the rim of the crater. The rims of the crater are near vertical – one should be very careful here.

The lava lake was small but absolutely fascinating. It had constant lava fountains rising up to 30 m high, the small lake had a constant movement, mesmerizing the visitors. It was even more impressive during the night. There were few places on Earth with similar experiences.

After a powerful eruption and several earthquakes, all lava lakes of Ambrym volcano have disappeared. We do not know if they will return…

Mbwelesu Crater (Marum Crater) is included in the following article:

Lava lakes of the world
Lava lakes of the world in 2019
Lava lakes of the world in 2019 / Wondermondo / public domain
In October 2019 we have seven existing lava lakes on Earth. Three more existed for a longer time in the recent past. Besides this, since the year 2000 short-lived lava lakes and lava ponds existed in 11 more places. Wondermondo has listed them all in this article.


  1. Ambrym volcano. Accessed on June 10, 2019
  2. Smithsonian Institution, National Museum of Natural History. Global Volcanism Program. Ambrym. Accessed on June 10, 2019
Mbwelesu Crater (Marum Crater) on the map
Travelers' Map is loading...
If you see this after your page is loaded completely, leafletJS files are missing.
Location, GPS coordinates: 16.2510 S 168.1366 E
Categories: Volcanoes, Lakes and streams, Places with meteorological phenomena
Values: Geology, Visual
Rating: 4.5 out of 10 stars
Where is located? Oceania, Melanesia, Vanuatu, central part of Ambrym Island, in the side crater of Marum Crater – Mbwelesu Crater
Alternate names Marum Crater (not very correct)
Height: around 1,334 m

Video of Mbwelesu Crater

GoPro, October 2014

Landmarks of Vanuatu

Lake Letas with Mount Gharat, Vanuatu
Lake Letas with Mount Gharat / , Wikipedia / CC BY-SA 2.5
Vanuatu is beautiful and impressive country. People of Vanuatu should be praised for the preservation of the natural landscape and their traditions thus showing that there is a noble alternative to Western civilization.


Mount Cleveland, Aleut Islands
Mount Cleveland / NOAA Photo Library, / CC BY 2.0

This category includes the most unusual and interesting volcanoes of the world.

Over the last 10,000 years in some 1,500 places around the Earth through the crust of the planet was emitted lava, ash, and gases from the mantle of Earth. Each of these places is an active volcano. Every year some 50 – 70 volcanoes are erupting, at any moment there are some 20 – 30 eruptions on-going.

Recommended books

Vanuatu: Far Flung Places Travel Guide

The only current detailed guide to the islands of Vanuatu, with invaluable information not just on the main islands, but also the more rarely visited outer islands. Including maps and detailed listings.

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