Currents and channels in the Maldives: kandu explained

Each Maldivian atoll is a ring of reefs and islands around a lagoon. The ring is not solid. It is broken by gaps of different widths and depths, and Maldivians call these gaps kandu. Many carry the word in their names, such as Vaadhoo Kandu between North Malé and South Malé atolls, or Emboodhoo Kandu on the north-eastern side of South Malé Atoll.

Conservation researchers working on shark and ray habitats describe kandu simply: they are recognised by strong current flow. One studied example, Emboodhoo Kandu, is about 2 km long, under half a kilometre wide and between 5 and 30 metres deep, according to the Important Shark and Ray Areas factsheet linked to the IUCN Shark Specialist Group.

Two words help when you read a dive briefing:

• Kandu – a channel through the atoll rim, or the open water between two atolls.
• Thila – a reef that rises from the seabed but stays below the surface, often found inside or near channels.

For how the atolls fit together, see our Maldives atolls guide.

Two forces drive the flow through a channel. They often work together and sometimes against each other.

Tides

Tides in the Maldives are small but steady. An environmental study held by the Maldives National University library, using more than 30 years of readings from the tide gauge at Hulhulé (the airport island), describes a mixed tide: usually two highs and two lows a day, of unequal size. The largest range recorded at that gauge is about 1.2 metres.

That sounds modest, but a whole lagoon fills and empties through a handful of gaps, so the water speeds up as it squeezes through. Flows tend to be strongest around new and full moon, when tides are at their largest.

The Maldives Meteorological Service publishes a tide prediction chart on its website, and runs tide stations at Hanimaadhoo, Hulhulé and Gan (as reported by Edition, June 2025). Local tides can arrive a little earlier or later than the Hulhulé figures, so treat them as a guide rather than a timetable.

Ocean currents and the monsoon

The Maldives sits across the path of the monsoon-driven currents of the Indian Ocean. Researchers note that the island chain interrupts this flow, which forces water through the channels. Broadly, the current comes from the east in the northeast monsoon (about January to March) and from the west in the southwest monsoon (about mid-May to November), with April and December as transition months.

Researchers also note that the strongest tidal currents can overpower the monsoon current at a channel’s outer edge, so conditions in one kandu can change quickly.

Divers talk about two states of a channel.

On an incoming current, grey reef sharks and other predators often hold position at the mouth, facing into the flow. Research on grey reef sharks in Pacific channels suggests they use the upward push of water over the reef edge to save energy. Whether the same is true in the Maldives still needs study.

An outgoing current carries water, and anything in it, away from the atoll and down the outer reef. Guides plan these dives carefully, because the flow can take divers off the reef and into open water.

The season matters too. The Manta Trust notes that reef mantas tend to feed on the eastern sides of the atolls in the southwest monsoon and the western sides in the northeast monsoon. Read more in our guides to sharks in the Maldives and manta rays.

Channel dives are among the best dives in the Maldives, and they are not beginner dives. The Divers Alert Network (DAN) recommends proper training before drift diving and suggests avoiding currents above about one knot until you have the training and experience.

What a good channel dive usually involves:

• A clear briefing. Your guide should explain the current direction, the entry point, the plan if you miss the reef and how pick-up works.
• A negative entry. You enter with little or no air in your jacket and go straight down, so the current cannot carry you past the reef.
• Staying low. Current is usually weaker close to the reef and behind ledges.
• A reef hook, where the guide allows it. Hook only onto dead rock, never onto live coral.
• Your own surface marker buoy. DAN describes a delayed surface marker buoy on a reel as a key skill for current diving, so the boat can follow you during your safety stop.
• Staying with your buddy. Separation happens fast in a channel.

DAN also warns about down-currents and up-currents. If water pushes you down, keep equalising; if it pushes you up, breathe out steadily. In either case, streamline yourself and hold onto rock if you can, avoiding coral. Recreational dives in the Maldives are limited to 30 metres under the Recreational Diving Regulation.

If you are new to diving, start with sheltered lagoon and house-reef sites and work up. Our learning to dive guide and the main diving in the Maldives guide explain how. Freedivers face the same flows; see freediving in the Maldives.

Feeding sharks and rays is illegal, whatever the current is doing.

Snorkellers meet currents too, especially at the reef edge of a local island, near the harbour gap and on trips to channel sites.

• Don’t snorkel a channel from the shore. Join a guided boat trip, where the boat follows the group.
• Never snorkel alone, and tell someone on land where you are going.
• Ask locally first. Fishermen, guesthouse staff and dive centres on the island know which way the water runs at different times.
• Wear fins, and a buoyancy vest if you are not a strong swimmer.
• Watch for boats. Harbour entrances and dredged channels are busy, and skippers may not see a snorkel.

If you feel yourself being carried away, don’t fight the current head-on. Stay calm, float, swim across the flow rather than against it, and wave for help. Call 911, the national emergency number, if someone is in trouble in the water.

Our snorkelling guide covers gear and where to start.

Wind and swell add to current. In the southwest monsoon the sea is generally rougher and visibility lower, and the Met Service issues warnings for strong winds and high waves. On days like these, guides may switch to sheltered sites inside the atoll. See weather hazards in the Maldives for how to read the warnings.

Dhiffushi sits on the eastern rim of North Malé (Kaafu) Atoll, the easternmost inhabited island in the country, with the open ocean on one side and the lagoon on the other. That position means its outer reefs feel the ocean directly, while the lagoon side is calmer. Local guides plan trips around the season and the tide, and the island’s manta spot, Manta Bay (Dhiya Adi Faru), is best visited with them. For dive and snorkel options from the island, see diving and snorkelling in Dhiffushi.