Spend a full day aboard the Poseidon visiting three outer Agincourt ribbon reef sites for guided snorkel tours and up to three scuba dives. Learn from a marine biologist, join citizen-science surveys, and experience remote coral gardens accessible from Port Douglas.
More ways to explore the area's outdoor wonders
The Poseidon slips out of Port Douglas at first light, engines steady as the coastline thins and the Coral Sea opens like a vast, blue promise. By mid-morning the catamaran ties to moorings on the outer Agincourt ribbon reefs, and the water invites a confident kick—coral bommies rising beneath glassy surfaces, fish weaving through fingers of staghorn.
Difficulty
moderate
Duration
8 hours
Fitness Level
Moderate fitness: comfortable swimming ability and ability to climb ladders and move on wet decks.
Wildlife
History
The ribbon reefs are part of the larger Great Barrier Reef system, an accumulation of coral growth atop submerged continental shelf structures; local Aboriginal and Torres Strait Islander peoples have long-standing cultural ties to coastal waters.
Conservation
The Great Barrier Reef Marine Park manages access and research permits; visitors are encouraged to follow reef‑safe practices and support local conservation programs.
Reserve your spot on the Poseidon Outer Great Barrier Reef Snorkeling and Diving Cruise from Port Douglas today and enjoy a trusted, highly rated experience designed to help you make the most of your adventure.
Use reef‑safe sunscreen
Apply a reef‑safe, high‑SPF sunscreen before boarding and reapply where allowed—traditional sunscreens harm coral.
Hydrate and layer
Bring a reusable water bottle and a lightweight cover-up for wind and sun between swims.
Follow reef etiquette
Avoid touching coral, feed no fish, and use the provided exits to reduce reef damage and safety risks.
Plan flights after diving
Observe no‑fly times: 12 hours after a single dive, 24 hours after multiple dives to reduce decompression risk.
Reef‑safe sunscreen
Protects skin and the reef during prolonged sun exposure on the tropic sea.
summer
Lightweight rash guard or wetsuit top
Provides sun protection and warmth in cooler mornings or after repeated swims.
spring
Sturdy reef shoes or deck sandals
Protects feet on slippery decks and when entering shallow rocky areas.
summer
Mask and snorkel (optional)
Personal gear often fits better than loaners and improves comfort for long snorkel sessions.
summer