Our Story

Reefs Unknown was born in the US Virgin Islands, where most people are familiar with the degraded nearshore reefs. Few are privileged to witness the expansive coral banks just a few miles offshore. These deeper mesophotic reefs are frequently ignored or completely unknown to science. Some are known only to the fishers who know where the catch is good.

These deeper reefs cover nearly twice the area of shallow reefs in the USVI, so how could they be so poorly understood and under-managed? The answer is lack of access. Divers require extensive training to safely reach the mesophotic zone, and these reefs are often far from shore in exposed conditions. We created Reefs Unknown to help bridge this gap. With our extensive experience working in this type of environment, we can ease the difficulty and work with our partners to complete research and provide management recommendations.

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  • Exploration

    Locating and studying undocumented reefs.

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  • Education

    Sharing findings with scientsts, managers and the public.

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  • Conservation

    Promoting further work on these ecosystems and including them in management plans.

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Our Team

Together we have over 20 years collective experience doing this work in the USVI and elsewhere. We have extensive knowledge and experience performing scientific research locally as well as planning and executing field missions to other locales including Pacific Panamá, Galápagos, Bermuda, and Bonaire.

We are designed to be a flexible, small platform that works with existing partners to expand their work to new depths and locations.

Viktor Brandtneris and Sarah Heidmann, founders of Reefs Unknown.

Viktor Brandtneris

Viktor Brandtneris on a research expedition to the Galapagos.

Viktor learned to dive at the age of 12 in a lake in St. Paul, Minnesota and from there kept moving south for warmer water. After studying marine biology at the University of Miami which included work in Panama, the Galapagos, and throughout the Caribbean, he moved to St Thomas to pursue his master’s degree in coral reef ecology. He’s been managing research teams, technical SCUBA diving, and data analysis on various projects for more than nineteen years and 3000 dives.

Sarah Heidmann

A scuba diver exploring coral reef underwater.

I fell in love with the ocean at the Monterey Bay Aquarium as a kid, and ever since I got SCUBA-certified in college, I’ve spent my career chasing opportunities to dive for research. My adventures have taken me to live and dive in Bonaire, Oregon, and now the US Virgin Islands, where I completed my master’s degree in tropical fish ecology. Now I’m a USCG-certified captain and technical rebreather diver, using those skills to pursue my interests in mesophotic fish ecology and conservation.

Board of Directors

Science Advisory Board

Kristin Rasmussen

Kristin Rasmussen serves on Reefs Unknown's Board of Directors. She is a marine biologist who specializes in marine mammals.

Kristin Rasmussen is a marine biologist who specializes in marine mammals. She received her MSc at Moss Landing Marine Labs on Monterey Bay in 2005. For over twenty years she has been studying two different humpback whale populations that breed off Central America. Kristin is the President of the USA branch of the 501(c)3 nonprofit Panacetacea, dedicated to the research, management, and conservation of the marine mammals of Panama. She is passionate about marine conservation and believes strongly in the mission of Reefs Unknown.

Andrew J. Hemmert

Andrew Hemmert serves on Reefs Unknown's Board of Directors. He is the President and owner of HMRT, LLC.

Andrew Hemmert is currently the President and owner of HMRT, LLC with a focus on commodity trading and logistics. The company is based in St. Thomas, USVI in partnership with the University of the Virgin Islands. He is a member of the St. Thomas Reformed Church Endowment Committee and a member of My Brother’s Workshop Technical Committee. Andrew has a BS in Management and Marketing from the University of South FL as well as an MBA from Nova Southeastern University. He has worked for various energy companies over the past 33 years in Florida, New York, Texas, and Colorado. He engages in various philanthropic endeavors. Andrew is an avid sailor and enjoys the outdoors.

Sara Dent

Sara Dent serves on Reefs Unknown's Board of Directors. She is a current Trustee of the Woods Hole Oceanographic Institution.

Sara is a current Trustee of the Woods Hole Oceanographic Institution, the world’s leading independent non-profit organization dedicated to ocean research, exploration and education. Operation positions in Maintenance and Repair and Traffic and Chartering Departments of the Chevron Shipping Company led to the interest in becoming involved with the Oceanographic. She is also the Board of the Clearwater Investment Trust, an investment company. Sara is currently on the Advisory Council for the World War II Memorial on the National Mall and the AFI/Silver Theater in Silver Spring, Maryland. She has also served on the board of the Rock Island Company as well as several foundations and schools.

Dr. Tyler B. Smith

Dr. Tyler Smith from the University of the Virgin Islands serves on Reefs Unknown's Science Advisory Board.

University of the Virgin Islands

  • Coral Reef Ecology

  • Mesophotic Reef Fisheries

  • Climate Change Refugia

Dr. Ariana Huffmyer

Dr. Ariana Huffmyer from the University of Rhode Island serves on Reefs Unknown's Science Advisory Board.

University of Rhode Island

  • Coral Assisted Evolution

  • Coral Thermal Physiology

  • Coral Symbiosis

Dr. Marilyn Brandt

Dr. Marilyn Brandt from the University of the Virgin Islands serves on Reefs Unknown's Science Advisory Board.

University of the Virgin Islands

  • Emerging Threats to Coral

  • Coral Restoration

  • Reef Fisheries Assessments

Dr. Daniel Holstein

Dr. Daniel Holstein from Louisiana State University serves on Reefs Unknown's Science Advisory Board.

Louisiana State University

  • Ocean Connectivity Modeling

  • Coral Reproduction

  • Mesophotic Coral Reefs 

A scuba diver explores a coral reef underwater, surrounded by large coral formations with a blue ocean background.

Frequently Asked Questions

  • Reefs Unknown is a 501(c)3 tax-exempt nonprofit organization founded in 2021, dedicated to exploring, researching, and conserving coral reefs throughout the Caribbean and the world. We focus primarily on the unique deep coral reef ecosystems called mesophotic reefs.

  • A mesophotic reef is a coral reef that exists beyond the limits of recreational scuba diving. These deep corals still rely on light for photosynthesis like shallow corals, but have different traits and adaptations because of the low light and temperature. The boundary depths where these reefs start and end are fuzzy, and often vary depending on the location, but are usually in the range of about 100 feet to 500 feet deep. They are well-studied in the Virgin Islands, the Cayman Islands, the Red Sea, the Chagos Archipelago in the Indian Ocean, Hawaii, and other locations. Mesophotic reefs can be found in many places you can find shallow coral reefs, but in many areas we don't know where they exist simply because we haven't looked.

  • In some locations, mesophotic reefs can look somewhat similar to shallow reefs, with some generalist species of fish and coral living in both locations. These species, however, usually have adaptations that allow them to live in the different conditions of the deep. In other locations, shallow and deep reefs can look completely different, with depth-specialist species of fish and coral that are not found shallow.

  • Fisheries, food, and conservation are all areas where mesophotic reefs can play a role. These ecosystems are usually farther from human impacts than shallow reefs, meaning they have fewer stressors. Because they are more removed from humans, they can be healthier ecosystems that support fish. Sustainable fish populations are key to healthy ocenas, as well as sustainable food for humans.

  • How can you manage a resource if you don't know where it is? We know that many fish consumed around the Caribbean are caught from mesophotic reefs, but we don't know how many more are out there (we suspect there are a lot), or the health condition of the reefs that support them.

  • Our team consists of Viktor and Sarah, our co-founders, have extensive experience researching mesophotic reefs in the US Virgin Islands, specializing in coral and fish, respectively. They started Reefs Unknown to bring their knowledge to other locations where mesophotic reefs are not well-studied.

    Our board of directors has a diversity of background knowledge in non-profit management and marine science work.

    Our science advisory board comprises accomplished coral reef scientists who help guide our scientific efforts.

  • We are planning a mission in partnership with NOAA and the University of the Virgin Islands to complete deep fish surveys in the Florida Keys. This is an expansion of an ongoing project in the US Virgin Islands called the Deep Coral Reef Monitoring Program, or DCRMP. To learn more, read our blog post about the proposed project.

  • We are currently a small organization, but we have big dreams. We are in the midst of planning our first missions. The best way you can help us right now would be to support us in the form of a donation. Please click here to donate. If you have advice, connections, or other ideas you'd like to share please reach out.

  • All donations made are tax-deductible and will directly fund our missions and infrastructure costs. Your contribution will help advance human knowledge of mesophotic reefs, inform conservation best-practices, and bring these amazing ecosystems closer to ocean enthusiasts everywhere.