Beneath the Waves: A Surprising Underwater Discovery

Researchers diving off the coast of Papua New Guinea have uncovered a remarkable deep-sea environment: a hotspot where hot hydrothermal vents and cold methane-rich seeps erupt side by side — a geological setup never recorded before. Located about 1,300 meters deep along the slope of Conical Seamount, near the island of Lihir, this hidden field stunned scientists with its unusual chemistry and thriving marine life.

Deploying the remotely operated vehicle ROV Kiel 6000 during the 2023 expedition aboard RV Sonne, the team from GEOMAR Helmholtz Centre for Ocean Research Kiel observed that hot water from below and cold methane-gas seepage from sediment beneath the volcano rise through the seafloor using the same pathways — so close that hot vents and cold seeps bubble from neighboring cracks only centimeters apart.

According to expedition lead scientist Philipp Brandl, this hybrid hydrothermal-seep system was total surprise: “We essentially have a hot vent bubbling right next to a cool gas seep — a combination that has never been described before.”

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An Underwater Oasis Brimming With Life

This unusual geological mix has created a deep-sea habitat teeming with life. The rocks and sediments around the vent field are densely carpeted with life: mussels, tube worms, shrimp, amphipods, and striking purple sea cucumbers. In some spots, the density of life was so high “you couldn’t see a single patch of bare rock,” according to the researchers.

Given the dominance of mussels, the researchers — with help from local observers — have dubbed the site Karambusel: ‘karambusel’ means “mussel” in Tok Pisin.

The team believes many of the organisms living there could be new to science — but only a dedicated follow-up expedition can confirm that fully.

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Geology, Gold — and Risk

Besides its biological marvels, Karambusel harbors geological secrets. Rocks around the vent field show traces of gold, silver, along with heavy elements like arsenic, antimony, and mercury. These deposits point to past high-temperature volcanic activity that once shaped the seabed — though current hydrothermal fluids are cooler.

But this hidden gem comes with a danger: the same metals that glint in the rock make the area attractive for mining. Indeed, there are existing mineral-exploration licenses, and a nearby gold mine already discharges waste into the ocean.

Such industrial interest could quickly disturb or destroy the fragile ecosystem that has taken millennia to form. The researchers emphasize the urgent need for careful marine spatial planning and protective measures before economic pressures irrevocably damage this unique site.

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Why This Discovery Matters

• New type of deep-sea ecosystem: The coexistence of hydrothermal vents and methane seeps — so tightly interwoven — challenges previous assumptions about deep-sea biology and geology. Karambusel opens a new window into how underwater ecosystems can form under extreme and mixed conditions.
• Biodiversity potential: With dense populations of mussels, tube worms, shrimp and likely unknown species, Karambusel could help scientists expand understanding of life’s resilience and diversity in extreme environments.
• Mineral wealth vs. conservation: The metallic deposits highlight a longstanding tension: valuable natural resources versus the need to preserve unique, fragile ecosystems. Karambusel stands at that crossroads.
• Conservation urgency: The discovery comes at a time when deep-sea mining interest is rising globally. Without early protection, unique habitats like Karambusel risk destruction before they’re fully understood.

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Looking Forward: What’s Next

Scientists call for a dedicated expedition to: