Human activity has reached almost every corner of the planet, from the depths of the Mariana Trench to the summit of Mount Everest.
Yet researchers say two remote locations in the Pacific Ocean may still stand apart.
The coral atolls of Bikar and Bokak appear to remain remarkably wild and largely untouched, according to a new scientific assessment.
Situated near the Marshall Islands, the isolated atolls could rank among the most intact ecosystems left in the region — and potentially anywhere on Earth.
‘This study establishes the first comprehensive ecological baseline for the newly designated National Marine Sanctuaries of Bikar and Bokak, covering everything from the atmosphere and land to shallow reefs and the deep sea,’ said lead author Dr Alan Friedlander, a marine ecologist at the University of Hawaii.
‘Bikar and Bokak are treasures not only for the Marshall Islands but for the entire planet. They represent a gift from the Utirik Atoll community, which has carefully protected these fragile environments for generations.’
Researchers say the coral atolls of Bikar and Bokak remain among the Pacific’s most genuinely wild and untouched environments
Bikar and Bokak are the Marshall Islands’ northernmost atolls, located roughly 72 miles and 239 miles from the nearest inhabited atoll. Bikar’s reef habitat is especially rich in marine life
Bikar and Bokak are the northernmost atolls in the Marshall Islands, positioned about 72 miles and 239 miles respectively from the nearest inhabited atoll.
In 2023, scientists conducted an extensive survey across the islands, surrounding waters and skies. Their work included counting seabirds and shorebirds, documenting vegetation, locating turtle nesting sites and examining coral reefs and fish populations.
Scuba diving surveys, underwater video, deep-sea cameras and a submarine allowed the team to assemble one of the most detailed biodiversity assessments ever made in the area.
The research later helped support the creation of a 48,000-square-kilometre marine sanctuary around the atolls in 2025 — the first national marine protected area established by the country.
‘These atolls contain extensive seabird colonies, mature native vegetation and active nesting grounds for turtles,’ Dr Friedlander said.
‘They also support substantial reef-fish biomass and large predators, coral-dominated reefs at Bokak, complex mesophotic habitats and unexpectedly varied deep-sea communities that remain poorly understood.’
Researchers identified 15 seabird colonies across the two atolls that were either confirmed or believed to be breeding sites.
Their surveys also recorded at least 266 reef-fish groups, 138 groups of fish inhabiting deeper waters and 79 groups of deep-sea fish.
Located near the Marshall Islands, Bikar and Bokak may represent some of the Pacific’s most intact ecosystems
Turtle nesting was found almost entirely at Bikar, where researchers recorded 132 green sea turtle nest pits
The survey documented at least 266 reef-fish groups, 138 groups of deeper-water fish and 79 groups of deep-sea fish. Pictured: A bumphead parrotfish at Bokak Atoll
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Scientists found 15 seabird colonies that were confirmed or thought likely to be breeding. Pictured: Brown boobies at Bikar Atoll
The team additionally recorded 15 groups of open-ocean predators, including sharks, jacks and wahoo.
Two of the species identified during the expedition could potentially be new to science.
Although the atolls share many species and environmental features, the researchers found clear differences between them.
For instance, almost all of the recorded turtle nesting occurred at Bikar, where 132 green sea turtle nest pits were found.
Bokak had the greater overall reef-fish biomass and was defined by reefs dominated by coral communities.
Bikar, meanwhile, contained a wider variety of algae.
By examining these ecosystems in such detail, scientists gained an unusually rare view of how tropical marine environments operate with very limited human disturbance.
‘These sites are among the strongest ecological reference systems available for understanding what has been lost in more heavily impacted places,’ Dr Friedlander said. ‘They can also provide essential knowledge for designing effective conservation and restoration programmes.’
Bikar, pictured from the International Space Station, supported a broader range of algae
Bokak recorded the higher reef-fish biomass and is characterised by coral-dominated reef communities. Pictured: An orange-fin anemonefish
The researchers combined scuba surveys, underwater video, deep-sea cameras and submarine observations to document the region’s biodiversity. Pictured: Giant clams at Bokak Atoll
‘The Marshall Islands government deserves recognition for taking the lead in protecting these globally important biodiversity hotspots, where human influence remains distant and marine habitats are full of life.
‘As human pressures continue to drive biodiversity loss, places that have escaped intense disturbance serve as essential refuges.
‘Large marine protected areas also function as globally significant ecological reference sites, helping scientists understand the structure and future direction of tropical ocean ecosystems.’
The study, published in the journal Frontiers in Marine Science, cautions that remoteness does not make Bikar and Bokak immune to global environmental change.
Warmer oceans, coral bleaching, rising sea levels and changes in marine productivity are increasingly reaching even the planet’s most isolated tropical reefs.
The conditions recorded in the survey will provide an important baseline for tracking ecological changes in the years ahead.
As truly undisturbed marine environments become increasingly scarce, the researchers say Bikar and Bokak offer an invaluable glimpse of how healthy tropical ocean ecosystems function.