Okinawa

Okinawa's Reef

The colour bands in the water are a map. Where the reef flat ends, where the drop-off starts, which beaches you can swim off and which ones you cannot, and why the boat trip is usually the right call.

A fringing coral reef seen from above, pale green over sand and dark over coral, with surf breaking at the outer edge — Okinawa · July 2022

Almost every Okinawan coast is fringed by a reef that runs a few hundred metres offshore and then stops abruptly. That one fact explains the colour of the water, where it is safe to swim, where the fish are, and why so many visitors spend a week on the islands and never actually see a reef.

Learn to read the bands and you can plan a day from a photograph.

At a glance

Season: Swimming season is roughly April to October. Water stays warm into November
Typhoons: July to October. Boat trips cancel at short notice; build a spare day in
Water temperature: Around 27–29°C in midsummer, 22°C in March
Equipment: A rash guard matters more than a wetsuit. The sun is the hazard, not the cold
Reef safety: Never walk on living coral; never swim out across the drop-off without a boat

The bands are a depth map

A wide fringing reef photographed from a headland, pale green over sand and dark patches of coral, with white surf at the outer edge — Everything inside the white line is reef flat — shallow, calm and walkable in places. Beyond it the bottom falls away.Okinawa · July 2022

From a headland the structure is obvious. Nearest the beach is sand at a metre or less, which reads milk-green. Beyond it the reef flat begins: a mottled field of coral heads and sand channels, one to three metres deep, which reads green and dark brown in patches.

Then there is a line of white — the surf breaking on the reef crest — and immediately past it the water goes navy. That is the drop-off, and it can be forty metres within a few strides.

The fish are concentrated in two places: the coral heads on the flat, and the wall at the drop-off. The sand in between is empty, which is why people who swim straight out from a beach often see nothing and conclude the reports were exaggerated.

Which beaches you can actually swim off

A rough stone path with a wooden handrail descending through low vegetation towards a reef — A reef overlook is not a beach access. Many of the best-looking coasts have no safe way into the water.Okinawa · July 2022

A beach with a managed swimming area has a netted enclosure, a flag system and lifeguards during the season. These are safe, shallow and usually fairly dull for snorkelling — the net is set inside the sand zone.

Unmanaged coast is where the good water is, and it comes with real conditions. The current that drains the reef flat at falling tide runs out through the channels at speed, and the surf line is not a boundary you can swim back over. Entry and exit points are specific rocks, not anywhere along the shore.

A limestone headland with a small pavilion on top, dropping into blue water with a boat below — Limestone coast: dramatic, photogenic and frequently with no way down to the water at all.Okinawa · July 2023

The boat trip is usually the right call

A long concrete causeway running out beside a lagoon of turquoise water towards a low green island — The lagoon side is flat and calm. The open side, a few metres away, is not.Okinawa · July 2022

Most of the famous snorkelling sites on the main island — the sea caves on the west coast above all — are reached from the water rather than the beach. A boat course costs more than a beach course and is worth it for two reasons that have nothing to do with comfort.

The first is that the boat runs when the beach entry does not. Swell that makes a rocky shore entry dangerous is frequently fine from a boat. The second is that you are taken to the coral, not to the nearest patch of sand with a car park.

Book it for the start of your trip, not the end. If the sea is up on your chosen day — and in summer it often is — you want days left to use the rebooking.

Beyond the main island

A broad shallow lagoon of banded turquoise water with a long low bridge crossing it in the distance — The outer islands are mostly reef flat, which is why their water photographs the way it does.Okinawa · July 2022

The Miyako and Yaeyama groups, an hour further south by air, sit on much broader reef platforms than the main island. The practical effect is that the shallow banded water extends for kilometres rather than hundreds of metres, and the bridges built between the islands cross all of it.

A white sand beach seen through a gap in dense coastal screwpine — Screwpine and beach morning glory hold the dunes together. Walking through them rather than around them is how they are destroyed.Okinawa · July 2023

These islands have far less infrastructure. Hire a car at the airport, carry water, and accept that the nearest shop to a good beach may be twenty minutes away.

Three things that protect the reef and your week

Wear a rash guard, not sunscreen, over your back and shoulders. Oxybenzone and octinoxate bleach coral, and the sun at 26°N in July will burn straight through a half-hour swim. Cloth is better for both.

Do not stand on the flat. A coral head takes decades to grow and a second to break. If the water is too shallow to swim, it is too shallow to be in.

Take nothing off the beach. Removing coral, shell and sand is restricted in Okinawa, and the inspectors at Naha airport do look.