As if floating through outer space, gazing at the surface of an unfamiliar planet, divers are awestruck by the view that unfolds below them. Although not quite alien, the kaleidoscopic expanse of animal colonies covering tropical seabeds is often compared to the otherworldly. Coral reefs might cover less than 1% of the ocean floor, but they are home to more than a quarter of all marine life.1 These beautiful ecosystems attract tourists from the world over, with tens of millions of trips made to the world’s reefs annually.2
Gorgeous as they may be, these natural wonders are not just for show. Coral reefs play a multitude of important roles in ocean and planetary health. They reduce coastal damage from storms and hurricanes, provide a significant portion of fish caught worldwide, and some coral even have promising pharmaceutical applications.3 Unfortunately, they’re also very fragile; since the 1950s, global coral cover has decreased by half.4 The usual suspects – warming oceans, rising sea levels, ocean acidification, and natural disasters exacerbated by human activity – contribute to the stress and degradation of coral reefs.
With more scuba divers being drawn to coral reefs worldwide, concerns about reef damage from diving have been on the rise. Night diving, diving with a camera, and diving with less direct supervision are shown to significantly increase the chances of divers damaging the corals.5 But, diving tourism also has the potential to be an educational experience, allowing individuals to learn about these environments and why they need protection, whilst also generating significant income for local communities.6 And this study shows that with proper management, you can minimise human damage to reefs while maximising the benefits that this type of tourism can provide.
The Caribbean experiment
Short-term studies have shown clear links between scuba diving and coral damage. As mentioned, corals can be very fragile and bumping into them not only causes physical damage but also increases their vulnerability to predation and disease.7 But these studies often use short timeframes, which limit their scope and lack diver-free areas that could help identify other potential reef stressors. To properly understand the long-term consequences of diving on coral reef health, researchers would ideally need to be able to compare their findings with previous ones from the same location, as well as compare reef damage to areas free from divers. Luckily, there is a place in the Caribbean that allows for exactly that.
Bonaire is an island in the Dutch Caribbean off the coast of Venezuela. The water surrounding the island, as well as the uninhabited islet Klein Bonaire (Dutch for “little Bonaire”), is part of the Bonaire National Marine Park (BNMP).8 To limit the impact of tourism on the marine life surrounding the island, the BNMP has taken significant measures over the years, including establishing no-diving zones and, more recently, no-fishing zones. These unique conditions allow scientists to rule out one potential reef stressor at a time to build a more accurate picture of human impacts on coral reef health.
A team of researchers not only leveraged the unique conditions of Bonaire, but also the fact that earlier research had already been done in the early 90s that investigated coral reef damage around the island.
The previous study by Hawkins et al., carried out between 1991 and 1994, found a small but significant decrease in massive coral (round, slow-growing coral that doesn’t get damaged by strong waves easily) both in zones open to diving and no-dive zones.9,10
Almost three decades later, scientists are able to compare these findings to current coral reef damage in a Bonaire that has much more tourism and additional reef management measures.
Leaving no stone unturned
In addition to sites closed to and open to diving, Bonaire introduced no-fishing zones in 2008. This allowed the research team to observe coral damage across 8 sites – 3 sites open to fishing and diving, 3 sites open to fishing only, and 2 sites open to diving only. The zones open to diving were further divided into high-use areas and low-use areas.
At each site, the researchers laid a 20 metre long tape measure onto the reef as a reference and randomly placed one metre squared frames called quadrats along the line. For the sites that allowed diving, the team surveyed 30 quadrats at each of the low-use and high-use zones. Within the quadrats, the team recorded measures of coral damage such as the number of dead coral, loose fragments, and percentage of coral cover as a whole.
To then compare their findings to the previous study, they needed to estimate the increase in diving pressure in the time period between the studies. So, the researchers used published numbers of visitors from annual reports. According to their estimates, diving pressure on Bonaire had increased more than 200% since the 90s. Now the stage was set to figure out whether and how much diving actually contributed to long-term coral reef changes in Bonaire.
Does diving drive damage?
The results found that all measures of coral damage had increased since Hawkins’s work in the 90s. Intuitively, one might point to the almost threefold increase in diving pressure as an obvious culprit. But interestingly, the study found no correlation between diving pressure and coral reef damage in Bonaire. There was no difference in the level of damage between sites open to diving and fishing and sites closed to diving. Even more surprisingly, low-use areas within sites open to diving and fishing had more coral damage compared to high-use areas.
This could be the result of measures taken by the BNMP to reduce possible damage from diving tourism to the coral reefs. Measures like banning the dropping of anchors and limiting the number of divers per boat, as well as mandatory pre-dive briefings ensure that divers do their best to avoid damaging the marine ecosystem. The impact of fishing on the reefs also appeared to be relatively low, as fishing in Bonaire is limited to artisanal fishing, which is traditional fishing done on a small scale. These smaller fishing boats are allowed to drop small stone anchors, which sometimes damage the corals, but the absence of large-scale industrial fishing meant that fishing wasn’t a major culprit of reef damage either.
The likeliest culprit
Apart from diving pressure, something far more consequential had also increased dramatically in Bonaire since the 90s: coral disease. In Bonaire alone, coral disease prevalence increased more than 50 times over the last two decades. One suggested cause of this is the increased frequency and strength of hurricanes and storm surges that cause coral to break and become even more vulnerable to disease, similar to the way humans are more likely to get sick when stressed and tired.
The emission of greenhouse gases due to human activity has resulted a global increase in land and ocean surface temperatures.11 The warmer temperatures in turn increase the frequency of hurricanes.12 The southern Caribbean, including Bonaire, is not exposed to hurricanes that often and the corals found there are not well adapted to their impacts. But as the seas get warmer, the frequency and strength of hurricanes are likely to increase, and so might their impact on the islands and their reefs.13
The BNMP’s exceptional reef management practices do a great job protecting the coral reefs from local stressors. However, the bigger drivers of coral damage can’t be addressed just by establishing no-dive zones and enforcing proper behaviour while diving. The large-scale driving factors of coral damage and disease, such as increasing global emissions and warming oceans, need to be tackled by large-scale, global action.
As bleak as this may all seem, all is not lost; the reefs around Bonaire are still awe-inspiring and are thriving in some areas, thanks to the measures taken by reef managers and the responsible divers that followed set guidelines. May the little pieces of paradise we have left serve to remind us of what we stand to lose. So the next time you’re near the sea, take a moment to consider the fragility of it all and remember that it’s not too late to find another way.
How to find another way
Regardless of our vicinity to the ocean and our participation in water sports, we’re all connected. That is to say that actions you take in your everyday life contribute down the road to ocean health. From choosing to walk or cycle instead of driving to shopping with reusable bags instead of using even more plastic, there’s always another way around the corner. Being mindful that we are not separate from the natural world but a part of it and acting accordingly can go a long way in protecting not just the beautiful coral reefs of the Caribbean but the Earth itself.
To find out more about corals, the threats they face, and ocean health in general, check out some of these resources:
Corals and coral reefs – a detailed article from the Smithsonian on all things coral https://ocean.si.edu/ocean-life/invertebrates/corals-and-coral-reefs
Protecting the Oceans: 10 Easy Ways You Can Contribute – a more complete list of things you can do to contribute to ocean health today. https://www.oceans-research.com/protecting-oceans-10-ways-to-contribute/
Coral disease – a guide to different coral diseases and how to identify them https://coralworldvi.com/marine-biology/coral-disease/
Chasing Coral – a documentary on coral bleaching supplemented by a website giving more detail on the issue and how you can take action. https://chasingcoral.com/the-film/
Article written by Hari Arevalagam
Photos taken by Tara Williams
Primary paper
Williams, T.R.G. et al. (2025) ‘Scuba diving pressure is not responsible for decadal coral decline in the Bonaire National Marine Park’, Journal for Nature Conservation, 86, p. 126905. doi:10.1016/j.jnc.2025.126905.
Other references
- MacPherson, R. (2023) Coral Reefs Need you, Smithsonian Ocean. Available at: https://ocean.si.edu/ecosystems/coral-reefs/coral-reefs-need-you.
- Brumbaugh, R. (2017) Protecting million dollar reefs is key to sustaining global tourism, The Nature Conservancy. Available at: https://www.nature.org/en-us/what-we-do/our-insights/perspectives/protecting-million-dollar-reefs/.
- Why are corals so important? (2024) Coral Guardian. Available at: https://www.coralguardian.org/en/coral-reef-important/.
- Eddy, T.D. et al. (2021) ‘Global decline in capacity of coral reefs to provide ecosystem services’, One Earth, 4(9), pp. 1278–1285. doi:10.1016/j.oneear.2021.08.016.
- Barker, N.H.L. and Roberts, C.M. (2004) ‘Scuba diver behaviour and the management of diving impacts on coral reefs’, Biological Conservation, 120(4), pp. 481–489. doi:10.1016/j.biocon.2004.03.021.
- Roche, R.C. et al. (2016) ‘Recreational diving impacts on coral reefs and the adoption of environmentally responsible practices within the scuba diving industry’, Environmental Management, 58(1), pp. 107–116. doi:10.1007/s00267-016-0696-0.
- Guzner, B. et al. (2010) Indirect impacts of recreational scuba diving: patterns of growth and predation in branching stony corals. Bulletin of Marine Science, 86(3), pp. 727–742. Available at: https://aurora.auburn.edu/bitstream/handle/11200/49965/gb727.pdf?sequence=1&isAllowed=y
- Bonaire National Marine Park (2025) Stinapa Bonaire. Available at: https://stinapabonaire.org/bonaire-national-marine-park/.
- Hawkins, J.P. et al. (1999). Effects of recreational scuba diving on Caribbean coral and fish communities. Conservation Biology, 13(4), pp. 888–897. doi.org/10.1046/j.1523-1739.1999.97447.xDigital Object Identifier (DOI)
- US Department of Commerce, N.O. and A.A. (2013) Corals: NOAA’s National Ocean Service Education, Corals Tutorial: Corals. Available at: https://oceanservice.noaa.gov/education/tutorial_corals/media/supp_coral03h.html.
- Reed, K.A., Wehner, M.F. and Zarzycki, C.M. (2022) ‘Attribution of 2020 hurricane season extreme rainfall to human-induced climate change’, Nature Communications, 13(1). doi:10.1038/s41467-022-29379-1.
- Hernández-Delgado, E.A. et al. (2024) ‘Stronger hurricanes and climate change in the Caribbean Sea: Threats to the sustainability of endangered coral species’, Sustainability, 16(4), p. 1506. doi:10.3390/su16041506.
- Knutson, T.R. et al. (2010) ‘Tropical cyclones and climate change’, Nature Geoscience, 3(3), pp. 157–163. doi:10.1038/ngeo779.
