The Around Africa Expedition is a collaborative expedition along the African coastline led by global ocean exploration non-profit organisations, OceanX and the newly established OceanQuest.

The expedition began at the end of January in Moroni, Comoros, aboard OceanX’s research vessel, the OceanXplorer.

The National Research Foundation–South African Environmental Observation Network (NRF-SAEON) is one of the parties participating in the Around Africa Expedition.

The first leg of the expedition, conducted in collaboration with NRF-SAEON, worked to map and conduct biodiversity surveys of Indian Ocean seamounts on the Madagascan Ridge and Agulhas Plateau.

The guest science team onboard included established and early career researchers from South Africa, Madagascar, Mozambique, Kenya, Tanzania, Comoros, Portugal, Brazil and Saudi Arabia.

It is believed that the measurement of the physical features and biodiversity around these seamounts will help to guide informed decisions on conservation and restoration efforts in these remote ocean areas.

Although these seamounts are located in the high seas, far from any human populations, their contribution as larval transport corridors are critical as this can support ecosystem resilience and the replenishment of fishing stock in deep-sea and coastal environments.

NRF-SAEON benthic ecologist Dr Lara Atkinson is part of the team leading the exploration of seamounts, including Walters Shoal and the Africana II seamount.

“A seamount is an underwater mountain that rises from the seafloor, but does not reach the ocean’s surface,” she explains.

“Seamounts are formed primarily by volcanic activity, often at tectonic plate boundaries or hotspots.

“Their height can range from hundreds to thousands of metres, depending on the intensity and duration of volcanic activity.

“They play an important role in influencing ocean currents, creating nutrient-rich upwellings that supports diverse marine life, including plankton, corals, sponges, fish and marine mammals.”

The OceanXplorer has two submersibles onboard the vessel, the Neptune and Nadir.

These three-person submersibles carried members of the research team to a depth of up to 500 m during the expedition.

The team also collected sample water to test for environmental DNA (eDNA), through the conductivity-temperature-depth profiler.

The eDNA detected in the seawater and sponge samples collected can provide a snapshot of the species present in the area.

Since its launch on January 30, the expedition has mapped uncharted ecosystems and gathered biodiversity data across Africa’s waters.

Among its most significant breakthroughs is the first-ever exploration of a previously known, but unexplored, seamount south of Walter’s Shoal along the Madagascar Ridge.

The submersibles conducted a visual survey on the area, revealing a deep-sea ecosystem that is home to corals, sponges and deep-sea species never before observed in this area.

Video surveys documented carbonate pebbles, deep-sea corals and species, such as the Brisingid sea stars, a chimaera, a dumbo octopus and a moray eel.

Sightings of Brisingid sea stars was a highlight, as they are characteristic of deep-sea ecosystems and serve as important indicators of ocean health.

Notably, two kitefin sharks were recorded during another dive in the north aspect of the seamount, to the delight of the team.

“Exploring the depths of Walter’s Shoal has been an extraordinary experience,” says Atkinson.

“Descending 500 m into the deep and seeing the seafloor unfold before my eyes was surreal – like exploring an underwater fynbos landscape of the Western Cape. Watching a large octopus play catch with the submersible’s lasers was a fascinating display of intelligence.”

Beyond its scientific objectives, the Around Africa Expedition is committed to building research capacity and fostering knowledge exchange across the continent.

OceanX and OceanQuest are working with a number of local institutions, including SAEON, the South African National Biodiversity Institute, the South African National Space Agency, the NRF–South African Institute for Aquatic Biodiversity and the University of Cape Town to advance ocean research and conservation efforts.