Where to dive in December

The month the year turns back

The usual answer to “where should I dive in December” is a list of ten warm places, and it could be pasted under any month of the winter. Our records say December is a month with a shape of its own. Every area we rate carries a rating for each of the twelve months, and when you ask which places become prime in a given month that were not prime the month before, December stands out: more places come back into their best season in December than in any month of the year but June.

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  <img src="https://reefwander.com/og/diagrams/season-turnover.svg" alt="Areas coming into their best season against areas leaving it, month on month. June is the biggest turn of the year; December is the second, and the first month after the autumn slide in which more places come into season than go out of it." loading="lazy">
  <figcaption>Diagram by Reefwander, licensed under CC BY 4.0.</figcaption>
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That matters because of what comes before it. From September to November the diving year slides. The Mediterranean shuts, the cold-water summer ends, the Caribbean sits in the tail of the hurricane season, and by November fewer than one place in five that we rate is at its best. December is the first month since the summer in which more places come into season than drop out of it.

It is not one sea recovering, either. Four things happen in the same few weeks. The Atlantic hurricane season ends on 30 November, and the Caribbean comes back. The north-east monsoon settles the Andaman Sea and the Maldives. The austral summer opens the cold, rough southern coasts of New Zealand, South Australia and Tasmania. And a set of animals whose season is the northern winter reaches the middle of it. The sections below take them in turn, the monsoon in two.

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  <img src="https://reefwander.com/og/diagrams/prime-calendar.svg" alt="The same ratings read as a share: the places at their best in each month. November is the low of the year; December climbs back from it, but fewer than one place in four is prime even so." loading="lazy">
  <figcaption>Diagram by Reefwander, licensed under CC BY 4.0.</figcaption>
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The recovery is real, and it is also uneven. Even in December, most of the places we rate are not at their best, and the last two sections are about that: where December is the wrong month, and the dates that do not flex when you book it.

The Caribbean comes back

The Atlantic hurricane season runs from 1 June to 30 November, and the Caribbean’s calendar is written around it. In November only a handful of the Caribbean areas we rate are prime; in December about half of them are, and by January most. The records give the same reason again and again: the storm risk is past, and the seas are calmer, drier and clearer.

Little Cayman is the cleanest example. Its calmest conditions and best visibility run from December to April, and Bloody Bay Wall is the dive those months are for: a lip at 5.5 m (18 ft) over a face that is, in sections, effectively vertical, with a careful profile reaching past 30 m and still returning a long dive. Randy's Gazebo on the same wall runs a chimney from 24 m to 9 m. On Grand Cayman, December to April is drier and calm enough for the exposed south side; Babylon on the North Wall is a pinnacle rising off the edge of the Cayman Trench.

Further south and west the pattern holds. Jardines de la Reina is steadiest from November through May, and its signature shark dive at Black Coral I and II is worked at 25 to 30 m. Dominica gives calmer seas and its better sperm-whale odds from November to May, with Champagne Reef a 4 m dive through volcanic bubbles. On Ambergris Caye (San Pedro), the dry season runs December to May.

Two places need a plainer word. Bonaire is in the table because it is rated prime from December, but it sits south of the hurricane belt and is diveable all year; its own record says the December-to-April prime months “mainly flatten the surface at the entries”. December changes little there. And Cozumel is rated only good in December and prime from January to April, with spotted eagle rays gathering from December to March: it is next month’s pick, not this one’s.

The Andaman Sea reopens

On the other side of the world the calendar is set by a park gate rather than a storm. The Similan Islands national park closes every year from 16 May to 15 October for the rainy season, and Mu Ko Surin National Park is typically open from 15 October to 15 May. The boats go back in mid-October, but the sea takes a little longer: December is the first month our records rate the Similan Islands and Surin Islands prime, and the calm stretch runs to March.

In the Similans, East of Eden is the busy hard-coral slope of the east side, and Christmas Point, at the exposed north end of the chain, has visibility at its clearest from December through April. Manta and whale-shark chances are best in the December-to-March stretch, and the Similan record calls them “luck rather than schedule”. King Cruiser Wreck, off Phuket, is already in its dry season from November.

Richelieu Rock is the exception inside the same parks, and the table shows it: rated good in December, prime from February to April, because its whale sharks are most reliable when the plankton peaks in those later months. Across the sea, Pulau Weh has been settled since October, and in India’s Andaman Islands the Barren Island run, where most of the mantas come, needs the settled December-to-April weather.

The Maldives dry season begins

The same monsoon turns the Maldives. The south-west monsoon reaches the islands at the beginning of June and lasts until the end of November; the dry season is the one associated with the winter north-east monsoon. For the central atolls, December to April brings the calmest seas and clearest water of the year, and Ari & Rasdhoo Atolls goes from fair in November to prime in December, and several of its neighbouring atolls turn prime with it.

It is worth being exact about what the season buys. The hammerheads at Rasdhoo Madivaru are, on the site’s own record, resident all year: the variable there is the hour, a dawn descent past 30 m, not the month. The Maldives’ mantas peak in the other half of the year, June to October, on the plankton the south-west monsoon pushes onto the western sides. What December changes is the sea itself, and on a channel dive like Moofushi Kandu, crossed only when the current is moderate, the sea is most of the dive. Fuvahmulah is the same case: its tiger sharks at Tiger Harbour are there in every month, and what the calm from December cuts is the choppy, cancelled days of October and November.

Further east the same turn of the monsoon brings the western Pacific’s dry season. Palau’s runs from November to April, and the manta traffic through its channel is most reliable from December to March; Blue Corner is diveable in any month. In the Philippines, Coron has its clearest water on the wrecks from December through April, and Anilao’s main season starts in mid-November, with January the peak for critter variety.

Summer in the south

The third sea is not one sea. It is the whole temperate south, where winter swell shuts exposed sites for half the year and December is when the boats start going out. Kaikōura is warmest and calmest from November to March, above a canyon that is 30 m (100 ft) deep at its head, then drops to 600 m and on to about 2,000 m (6,500 ft), only about a kilometre off the shore.

That rating is about the sea, not the animals. Kaikōura’s sperm whales and seals are there all year, and its dusky dolphin pods are biggest from June to August, the months the diving rates weakest. The same is true at Rapid Bay: the leafy seadragons under the Old Rapid Bay Jetty are resident and can show on any dive, and December to March is simply when the sea lets you work with them. In Tasmania, Hippolyte Rocks needs a flat, westerly day, which summer gives more often; at Lord Howe Island, Balls Pyramid is dived on the days the sea allows, and the warm current that brings the calmest, clearest water peaks from December to April.

Some southern animals are seasonal. At The Needles off Byron Bay, leopard sharks gather from about December into April. Off Stewart Island, the cage boat for great white sharks at Edwards Island lists a season from mid-November to June; it is a surface cage on surface-supplied air, and from July into October the Foveaux Strait is effectively shut. On the Antarctic Peninsula, the tour season lasts from November to March, and the penguin peak our record gives is December and January. Rapa Nui (Easter Island) joins them: calmest and warmest from December to March.

One southern site is a case where its own record matters more than the area’s rating. Quarter Mile Reef at Sodwana Bay carries its own seasons: from December to March, pregnant ragged-tooth sharks spend time on the reef while they gestate. But the same record says the reef is closed to diving while the sharks are monitored and left to settle, and the site’s own rating is prime in January and February and only good in December. Ask before you plan around it.

The animals that only come in winter

A last set of December places has nothing to do with calm water. These are the animals whose season is the northern winter, and December sits in the middle of it.

At Skjervøy, above the Arctic Circle, the orcas are in the fjords because the herring are: the reliable window runs from November into January, in water of 4 to 13 °C, and it ends when the herring disperse in late winter. At Crystal River in Florida, the manatees need water warmer than 68 °F (20 °C) to survive, and when the Gulf drops below it they crowd into the springs of Kings Bay; King Spring, a 60 m basin with its vent at about 20 m, logs manatees more often than any other animal.

Two whale-shark seasons fall in December. In the Gulf of Tadjoura, the winter plankton bloom draws juveniles in along the shore at Arta Beach from November to February, peaking in December and January, on a breath-hold rather than scuba. At St Helena, adult whale sharks of both sexes visit in reliable numbers, which is unusual anywhere else; the island’s government puts them there usually from November, peaking in January and February, and they are met on snorkel. The dive for the rest of the day is a wreck like Papanui, a 1911 steamer in 13 m of James Bay.

In the Pacific, Yonaguni’s scalloped hammerheads school from December to March, and the Yonaguni Monument is dived on the same trips when the wind lets the boats out. At Tiputa Pass, great hammerheads join the grey reef sharks in the southern summer, December to March. And at Kona, from December the humpbacks are present, more often heard singing underwater than seen, and at Maui, Molokini & Lānaʻi they fill the channel from December to April. The manta night dive at Garden Eel Cove runs in every month.

Those colours are ratings for diving conditions at each site’s area: sea state, whether the boats run, how clear the water tends to be. No site on the matrix carries its own calendar; each inherits its area’s. Read the December column and the Caribbean, Andaman, Maldivian and southern rows turn together, which is the whole argument of this guide in one strip.

Where December is not the month

The same ratings that make December a turning point say plainly where it is not one. The Mediterranean is shut: none of its areas is rated prime between November and April. In the northern Red Sea, Sharm El Sheikh — Ras Mohammed is rated fair in December, when winter winds make the Tiran crossings choppier, and the Brothers & Daedalus liveaboards are off entirely.

Two famous shark islands have just dropped away. Cocos Island and Galápagos — Darwin & Wolf are rated prime from June to November, the cooler, nutrient-rich season when the hammerhead schools are densest and the whale sharks arrive, and good from December. The December-to-May half is calmer and clearer, with fewer sharks at Cocos and few whale sharks at Darwin and Wolf. That is a fine trip, and a different one.

Komodo shows the rating and the animal pointing in opposite directions. Its diving is rated good in December, because its best visibility comes with the June-to-October upwelling; its mantas are most reliable at the southern cleaning stations in exactly the wetter December-to-March months it rates lower. Our month-by-month guide goes through what a month rating means, and what it does not. Revillagigedo (Socorro) is similar: good in December and prime from January, with its liveaboards already sailing and the humpbacks due from late January.

Booking a December trip

The other thing that does not flex is the holiday itself. Christmas and New Year fall inside the peak of both the Caribbean and the Maldives seasons. A Grand Cayman operator calls November to April the peak diving season and advises booking accommodation well in advance, and a Maldives resort advises booking the festive weeks three to six months ahead to secure a villa and seaplane transfers. If the dates are fixed, fix the boat first.

December rewards the same order of planning as any month, and more of it. Decide which of the four seas you are travelling to, then check the site’s own record rather than the area’s rating for anything that depends on an animal, and then book the one thing on the trip that has a gate or a timetable. Everything else can move.