Sunday 17th February

Conditions aboard ship today were much more reminiscent of the north Atlantic than the Caribbean: the weather front hit just as expected and we were soon rolling among whitecapped waves. The seas are nothing dramatic compared with what we've experienced in our Southern Ocean expeditions, but a contrast from the flat calm that we have enjoyed here so far.

I actually find it reassuring to hear the rhythmic creaking of fittings again, and the lullaby motion is soporific. As a consequence of the conditions, we moved 45 nautical miles south overnight to begin our hydrographic survey, which will investigate the source of the deep ocean water and currents over the volcanic rift.

Mini-tour of the RRS James Cook: from Principal Sci quarters,
down to main lab, through deck lab, to ROV control

In the present weather we have been picking our way back north, stopping at key locations to deploy the CTD probe and measure the temperature, salinity and currents throughout the water beneath us. The temperature and salinity provide a "fingerprint" for the deep water here, which physical oceanographer Kate Stansfield will use to identify its source. There are very few previous measurements of deep ocean currents in the region, and this investigation may also help us to understand the connections between colonies of deep-sea creatures in the Cayman Trough and elsewhere.

The pause in ROV dive operations has also given us time to take stock of samples and data collected at the Von Damm Vent Field, and refine plans work at the deeper Beebe Vent Field. We should finish our hydrographic survey and return to the Beebe Vent Field on Tuesday morning, when the weather is expected to moderate and may allow us to resume diving with the Isis ROV.

February 2013