A 3-D image of the RMS Rhone.

The Virgin Islands in 3D

A state of the art marine mapping project is bringing the BVI’s underwater world into sharp focus.

Koen Vanstaen on the Rhone Ranger

Over an 18 month period starting in July 2014, a group of underwater geologists, hydrographic surveyors and National Parks Trust personnel set out on an unprecedented mission to survey the BVI’s seabed, update its navigational charts and determine the extent of the area’s marine biodiversity. Using the National Parks vessel the Rhone Ranger and utilizing state of the art equipment, the project covered a 13.5 sq mile area off the coast of Tortola; the first seabed survey of its kind in the British Virgin Islands.


With modern acoustic survey tools and sophisticated underwater cameras, the team has produced eye-popping 3-D underwater images bringing the BVI’s seabed to life in unprecedented and surprising ways. A historic shipwreck not previously noted on local sea charts and an 800 percent increase in sea grass bed areas – vital for the protection of fisheries nurseries and marine life habitats – are among the project’s unexpected finds.

The undertaking is a collaboration between the UK Hydrographic Office, the Centre for Environment, Fisheries and Aquaculture Sciences (Cefas), also based in the UK, and the VI National Parks Trust.  “The aim is to see what is living in these areas of the seabed,” explains Koen Vanstaen, Cefas Group Manager. While the researchers have uncovered lots of barren sand, they have also found previously unmapped expanses of coral reefs and sea grass beds bursting with marine life.

A geologist by profession, Koen says he first entered the field to look below the land’s surface, “but what now drives me is what lives on the seabed and why it is there. Learning what is below the surface lets us determine what is valuable and what needs to be protected. For the first time we have produced a map of the underwater communities, coral reefs and sea grass beds in the Sir Francis Drake Channel.”

As it happens, sea grass beds are an essential component of the marine ecosystem. Not only are they rich in biodiversity, they act as fish nurseries, and importantly, are highly efficient at storing carbon. Impressively, sea grass stores carbon at a rate 35 times faster than a rain forest, making the protection of these areas yet another way to mitigate global climate change.

The resulting information will establish a baseline of the BVI’s seabed as it is now, and allow the Virgin Islands National Parks Trust and other government agencies to monitor future changes. Changes can be negative (coral reef deterioration caused by environmental stresses such as coral bleaching) – or positive (a formerly damaged reef that now shows sign of recovery).

At a 2013 meeting of SOLAS (Safety of Lives at Sea) attended among others by representatives of the UK Hydrographic Office, the BVI Ports Authority and the VI Shipping Registry, it was noted that the Territory’s navigational charts were out of date. While some bathymetric information on BVI charts was correct, other information, which dated back to the 19th century when lead lines were used to determine depth, was not. With ever-larger vessels traversing local waters, accurately updating these charts had become a priority, and the UK Hydrographic Office brought in Cefas to carry out the survey work. The VIs National Parks Trust, concerned about reef damage caused by ship groundings, along with other environmental interests, was also brought in as a project partner.

Funding was sought through the Darwin Plus, a UK government grants scheme that helps to protect biodiversity and the natural environment. This broadened the scope of the project from updating navigational charts to charting marine biodiversity. A recent visit by the cruise ship Queen Mary, which draws 10.5 meters, underscores  the need for accurate charts. One of the first areas surveyed by the team was a well-used shipping channel between the Sir Francis Drake Channel and Road Harbour. The original navigational charts, in use by mariners for decades, showed a depth in an area near Brandywine Bay of 9.8 meters. But when resurveyed, it was determined to be 10.9 meters. “Although, there will always error in any survey, what we do with the information is important,” explained Nancy Pascoe, Deputy Director of the VI National Parks Trust. “For instance should the BVI Government deepen this section of the approach to Road Harbour to prevent a potential collision?”

Hans Creek off Beef Island is a fisheries protected area and is home to many different species of sea life. Recent surveys have shown that reefs at the location are more extensive than had first been believed. Enhancing this protected area could be an environmental win win – not only maintaining the BVI’s marine biodiversity but also helping to nurture its fishing industry.

Fin Fun Peters in front of the Cefas research
vessel Endeavour in Lowesoft, England


The survey was divided into two parts. The first, the hydrographic survey, took place on the Rhone Ranger from July 18th to August 6th 2014, and a video and photographic survey from the 10th to the 20th of August. Researchers and personnel from Cefas; the UK Home Office; and the UK Hydrographic Survey took part in the project. Finfun Peters, Marine Coordinator for the National Parks Trust, also took part in the project.

one of the 5000 images illustrating the BVI’s seabed and marine ecosystems


Among the leading edge equipment aboard the boat was a multi-beam echo sounder, which yields information on a much larger swath of the seabed than previous technology. The three-dimensional imaging also offers unprecedented information on seabed features, notably the 1867 shipwreck, the RMS Rhone, a top BVI dive spot which lies in approximately 40 to 80 feet of water within the Rhone Marine Park off the western side of Salt Island. From shipwrecks, to reefs and rock outcrops, the vivid multi-colored images bring these underwater features to glorious life. In all, over 5,000 photographs illustrating the BVI’s seabed and marine ecosystems were taken.

“I was impressed with the detail you can get from this equipment,” declared Nancy Pascoe. “It was exciting to see the Rhone in such detail. I was skeptical at first, but when you see the imagery it is both very impressive and highly useful.”

The mapping project will be ongoing. Additional funding is being sought and Finfun who went on a training course at Cefas’s UK headquarters in Lowesoft, Suffolk (which included time in the Irish Sea aboard their 74 meter research vessel, Endeavour) will be able to maintain the project’s momentum even when Cefas personnel are not in the BVI.

Lynda Varlack, Director of the VI National Parks Trust, stated that she was very pleased with the outcomes of the project. “Ultimately we will be better able to apply the knowledge gained to making better informed and relevant marine management decisions.”

The project’s information has been digitally shared with various government agencies including Conservation and Fisheries, Town Planning, the Ports Authority, the Shipping Registry and Disaster Management.

For would-be underwater explorers, Cefas has posted its underwater exploration videos on YouTube, offering a unique up close view of the BVI’s seabed including coral reefs, sea grass and other features. Go to www.youtube.com and search for “BVI Underwater – Darwin Plus.”


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