Tuesday 19th February

At dawn we made our planned rendezvous, details of which will follow later this week. With calmer seas and the welcome reappearance of the Sun, we then launched the Isis ROV at the Beebe Vent Field. The vehicle has been configured again for collecting samples, having previously completed the mapping dive here.

At 1545h local time, the ROV reached the seafloor 5 km beneath us. The landscape that greeted us was a stark contrast to that of the shallower Von Damm Vent Field. Most of the ocean floor resembles a "lunar" landscape, light grey in colour thanks to the sediments that rain softly from surface waters far above. But the seafloor around the Beebe Vent Field resembles a "martian" landscape, strikingly red in colour because of the iron-rich mineral particles created by reactions between the hot vent fluids and surrounding seawater.

Red-stained sediments around the Beebe Vent Field; the two laser dots are 10 cm apart

Shortly after starting to cross this red-tinged landscape, we also encountered blocks of green minerals, rich in copper and also a product of the vent fluids. The vivid colours highlight a key difference between the vents here and those at the Von Damm Vent Field. The fluids here at the world's deepest known vents are much hotter and richer in dissolved metals, forming different minerals as they react with seawater.

At these vents, the mineral spires are spectacular: two storeys tall, slender and twisting, looking like solidified columns of the smoke-like fluid roiling out of them. Early in the dive we managed to locate a set of vents that we first saw in April 2010, and which our US colleagues visited in January 2011. Surveying those spires again with our high-definition video cameras should show us how quickly the patterns of life change here.

Back at the slender spires of Beebe Vent Field

Once the remotely operated vehicle is at the seabed, our work begins, as does the countdown that governs its return if we are to keep to the schedule for the expedition. As the midnight watch-change approaches, we still have much to do on this dive, and the heat and tension in the shipboard control centre are rising.

February 2013