Vicki Ferrini from Columbia University in the US, is a specialist at processing data from the side scanning sonar. In the photo taken from the shelter on the lake shore, she is showing her american colleagues some of the images that she has produced shortly after downloading data from the last AUV mission. Sharon Walker (left), Dan Fornari (just behind Vicki) and Amy Kukulya (right).

The image that Vicki has produced is an oblique side view of the lake floor, with a vertical scale of about 50 metres (the water depth). The amazing detail of the scan is visible in this image. You can see lots of little pock mark craters on the lake floor with streams of bubbles rising vertically above them. Obviously this area is hydrothermically very active. A lot of the emitted gas gets dissolved in the lake water before it reaches the surface, especially when it originates from vents at relatively deep levels in the water.

As the project reaches its final stages, the results of all the different surveys are being combined to fill out a fascinating picture of the Rotomahana hydrothermal system and present day bathymetry (lake floor topography). As project leader Cornel de Ronde keeps an overview and guides the activity of the different teams. (This photo Sharon Walker)