Low Isles is Port Douglas's closest Great Barrier Reef destination: two small coral cay islands, Low Isles and Woody Island, sitting on an inshore reef just 15 km off the coast. Visit Port Douglas Daintree describes the islands as surrounded by about 55 acres of reef with some 150 species of hard coral, although soft corals dominate. A heritage-listed lighthouse has operated on Low Isles since 1878, and the island houses a small museum and a research station.

The reef is shallow and easily accessible, which makes it ideal for snorkellers of all ages and abilities. Snorkelling begins right off the beach, over a mix of seagrass, sand and coral bommies in water a few metres deep. The turtle population is prolific, and underwater turtle sightings are common for snorkellers – green turtles in particular feed on the seagrass around the island.

Among the corals you can expect parrotfish, angelfish, damselfish, clownfish, trevally, sweetlips and moon wrasse. The islands are culturally significant to the Kuku Yalanji and Yirrganydji peoples, and the reef was the site of the landmark 1928–29 Great Barrier Reef Expedition led by Maurice Yonge, one of the first scientific studies of a coral reef ecosystem. As an inshore reef, Low Isles has lower visibility than the outer reefs, typically 3–10 m, and conditions depend heavily on weather and tides.

The coral is hardier and more turbid-tolerant than on the outer reefs. For certified divers seeking walls and big fish, the outer reef is a better option, but for families, first-time snorkellers and those wanting a short trip, Low Isles is excellent. Tours range from half-day trips to full-day sailing excursions, many including glass-bottom boat viewing, guided snorkelling with marine biologists and time on the island.

Low Isles trips leave Crystalbrook Superyacht Marina, Wharf Street, Port Douglas, most mornings (Sailaway, Quicksilver Wavedancer, Calypso and others); half-day and full-day options are available. Park at the marina car park or in surrounding streets, or use the operators' pick-ups. The crossing is only about 15 km and takes around 30 minutes by fast boat, longer under sail.

Vessels moor in the lagoon on the western side, guests are ferried ashore, and snorkellers enter from the beach or from the boat. There are no facilities for independent visitors beyond the lighthouse precinct; private boats must use public moorings and observe zoning.

Low Isles is an inshore reef and much more affected by weather and run-off than the outer reef. The lagoon on the western side gives shelter from the south-east trades, so trips run in most conditions, but winds over about 25 knots make the crossing rough and stir up the shallow water, cutting visibility to a few metres. Heavy wet-season rain (December–April) sends river plumes from the Mossman and Daintree rivers across the reef, reducing visibility further.

Best on calm days around high tide, when there is more water over the reef flat. Stinger season is November–May and this inshore location is higher risk – stinger suits are essential. Cyclone season November–April.

Snorkel from the beach or boat with the guide over the reef flat and edge on the western side, working along the coral bommies at 1–4 m and watching for turtles on the seagrass and reef. Stay inside the marked area and return to shore well before the tide drops.

Sailaway – daily sailing/snorkel trips; Quicksilver Wavedancer – daily Low Isles trips; Calypso Reef Cruises – Low Isles snorkel trips ('only 30 mins from Port Douglas'); other small operators run half-day tours. Primarily a snorkel destination; introductory/shallow dives offered by some operators.