Coral reefs of the Maldives: how they work and how to help

In the Maldives, the reef is the country. The white sand is mostly broken-down coral and shell, and the islands are low piles of reef rubble and sand heaped up by waves. Most land sits only a metre or two above the sea.

Reefs do several jobs at once:

• Coastal defence. The outer reef breaks ocean swell before it reaches the shore.
• Food. Reef and lagoon fish feed island families, and tuna fishing relies on bait fish caught in shallow water.
• Tourism. Snorkelling, diving and boat trips all depend on living reefs.
• Sand supply. A healthy reef keeps producing the sand that beaches and islands need.

That is why reef health sits at the heart of the debate on rising seas. Our guide Is the Maldives sinking? explains that side of the story.

The English word “atoll” is widely traced to the Dhivehi word *atholhu*, one of the few Maldivian words that went global.

The best-known explanation of how atolls form comes from Charles Darwin, in his 1842 book on coral reefs:

1. A fringing reef grows around a volcanic island.

2. The volcano slowly sinks, while the coral keeps growing up towards the light.

3. The volcano disappears beneath the sea, leaving a ring of reef around a lagoon: an atoll.

Later drilling on Pacific atolls found volcanic rock deep beneath reef limestone, which supported Darwin’s idea, and scientists now add that ice-age changes in sea level also shaped the reefs. The Maldives is a chain of these reef rings on an underwater ridge, each with many smaller reefs inside. Our Maldives atolls guide covers how the 26 natural atolls are grouped for administration.

You will hear Dhivehi reef words in the names of dive and snorkel sites. Usage varies a little between atolls, so treat these as common meanings:

Currents in the channels bring nutrients, which is why sharks, rays and big shoals gather there. For a visitor on a local island, the easiest reef is usually the house reef, where the shallow lagoon drops into deeper water.

A coral is a colony of tiny animals called polyps. Most reef-building corals host microscopic algae in their tissue. The algae use sunlight to make food and share it with the coral, which gives them shelter in return. The algae also give corals much of their colour. This partnership is why reefs need clear, shallow water, and why they are so sensitive to heat.

When the sea stays too warm for too long, corals expel their algae and turn white: this is bleaching. A bleached coral is not dead yet. If temperatures drop in time, the algae can return; if the heat lasts, many corals starve and die. The Maldives has seen three major events:

• 1998. A strong El Niño pushed sea temperatures far above normal. Surveys recorded very heavy coral loss, especially on shallow reefs, though many reefs recovered over the following years.
• 2016. Another global heat event. A survey led by the Maldives’ Marine Research Centre with the then Environmental Protection Agency and IUCN found that about 60% of coral colonies assessed were bleached, and up to 90% at some sites. The Maldives Marine Research Institute (MMRI) has since reported a figure of 73% of corals bleached in 2016 from its own study.
• 2024. During the fourth global bleaching event, MMRI warned in March that the Maldives was at “watch level” and that local bleaching had begun. Mass bleaching was later reported from several atolls, and studies of the damage are still being published.

Reefs can recover, but they need time between heat events, and those gaps are getting shorter. MMRI has also warned that large land reclamation projects can slow recovery after bleaching. If you see patches of white, you may be looking at bleached or recently dead coral.

Most damage from visitors is avoidable. These habits make a real difference:

• Never stand on coral. Even a single step can break colonies that took years to grow. If you need a rest, float on your back, or find a patch of sand.
• Wear a snorkel vest if you are not a confident swimmer. A buoyant swimmer doesn’t need to grab or stand.
• Watch your fins. Keep your legs up and stay well above the reef, especially at low tide.
• Don’t touch, feed or chase marine life. Feeding fish upsets the reef balance, and feeding rays and whale sharks is banned in the Maldives. See our guides to sea turtles and marine life for etiquette.
• Take nothing. Leave coral, shells and dead coral pieces on the beach and in the water. Many marine products need a permit to leave the country, according to Maldives Customs, so don’t buy or collect them.
• Anchors on sand, never on coral. Boat crews should use a mooring buoy or anchor on sand.

Our snorkelling guide covers kit and currents, and the diving guide covers buoyancy.

What about “reef-safe” sunscreen?

The honest answer is that the science is not settled. A 2022 report by the US National Academies of Sciences, Engineering, and Medicine found there was not enough evidence to say how sunscreen ingredients affect coral reefs, and it called for more research. Lab studies have linked some filters, such as oxybenzone, to harm in young corals, but real-world effects are unclear, and “reef-safe” is a marketing label, not a regulated standard.

The sensible approach: keep using sun protection, because sunburn here is fast and serious. Wear a rash vest so you need less cream, apply it well before you swim so less washes off, and if you want extra caution, pick a mineral sunscreen without oxybenzone.

You don’t need a resort to snorkel a good reef. Many local islands have house reefs within swimming distance, and short boat trips reach coral patches and thilas inside the atoll.

On Dhiffushi, on the eastern rim of North Malé Atoll, the Coral Garden is a shallow reef near the island that suits beginners, and there is a guided Coral Garden snorkelling trip. Go with a local guide if you are unsure of currents.

Snorkel shallow reefs at mid to high tide, so there is more water between you and the coral. Seas are often calmest in the dry northeast monsoon, roughly January to March, though reefs can be snorkelled all year: see when to visit.

MMRI, the government’s marine research body, has asked the public to report white or bleached coral through its website during bleaching alerts, and the 2016 national survey drew on data from divers and citizen scientists alongside expert teams.

• Take photos with context: the date, reef or island name and rough depth.
• Report widespread bleaching to MMRI through its official channels.
• Join a beach or reef clean-up if your island runs one.

For the bigger picture of travelling lightly, read our responsible travel guide.