Poseidon Outer Reef Cruises departs daily from Port Douglas to visit 3 different and unique reef environments. Our range of over 30 spectacular and exclusive reef sites at the Agincourt ribbon reefs and Escape Reef, enables us to offer some of the very best day boat diving.

With clear outer reef waters, beautiful corals and incredible marine life diversity, the Agincourt ribbon reefs offer the opportunity to snorkel and dive in some of the most pristine and special places on the entire Great Barrier Reef. Enjoy unlimited snorkelling in this marine wilderness, first time divers can try an introductory scuba dive, and certified divers can experience up to three dives.

Poseidon has limited passenger numbers to ensure personalised service and attention. Whether you choose to snorkel or dive, with an amazing array of quality reef sites, attentive and friendly crew, the comforts aboard and our special permit to swim with the Dwarf Minke Whales, Poseidon offers you the perfect setting to enjoy a day on the Great Barrier Reef.

Instant Booking & Mobile Friendly Tickets
Check availability & book here to secure your place on Poseidon.
Pre-booking is essential. Please do not turn up on the day without a booking.

What makes Poseidon Great

  • 3 Outer Barrier Reef spectacular destinations
  • Guided snorkel tour with Marine Biologist
  • Swim with Minke Whales - (seasonal) 
  • Poseidon has been awarded one of the few permits to swim with Dwarf Minke Whales. These friendly mammals are regularly encountered from May to August, while their larger cousins, the Humpback Whales appear from July to September. 

Daily Departure Times

  • 8.30am Reef Marina (Port Douglas) Return 4.30pm


  • Return Hotel transfers from Port Douglas accommodation
  • Morning and afternoon tea with muffins, fresh fruit and cakes
  • Buffet luncheon including prawns, roast chicken, roast beef, ham, selection of three salads, fresh bread and condiments
  • 3 different reef sites at Agincourt Ribbon Reefs
  • All snorkel equipment and tuition (inc. prescription masks)
  • Guided snorkel tour with Marine Biologist
  • Lycra suits and floatation devices
  • Freshwater showers

Your Day With Poseidon Cruises


Vessel boarding at the Reef Marina, Port Douglas (see map) 
Complimentary tea, coffee served until departure, muffins & focaccia


  • Depart for Outer Barrier Reef


  • Arrive at 1st Agincourt Reef Site


  • Transit to 2nd Agincourt Reef Site


  • Arrive at 2nd Agincourt Reef Site


  • Buffet lunch served


  • Transit to 3rd Agincourt Reef Site


  • Arrive at 3rd Agincourt Reef Site


  • Afternoon tea served


  • All passengers board for final passenger count


  • Commence return journey


  • Arrive at Reef Marina

Poseidon Vessel
The vessel features a large air-conditioned main saloon, a spacious top sun deck and wheelhouse salon, and a purpose built rear deck with a lowering transom which makes access to and from the water extremely easy and un-crowded.  Maximum number of 84 passengers if full.  

Certified Diving on Poseidon
The clear outer reef waters, beautiful corals and incredible marine life found at the Agincourt ribbon reefs, 70km north east of Port Douglas and on the very outer edge of the Great Barrier Reef, enable us to offer some of the very best possible day boat diving for both the seasoned and novice diver.

Experience up to 3 dives at 3 different and diverse reef locations.
Large tanks and computers for extended bottom time.

Certified divers can enjoy up to 3 dives on a day dive excursion with Poseidon. This includes drift and wall dives, isolated pinnacles surrounded by pelagic fish and coral gardens with their endless variety of colourful wrasses, cods, parrot fish, clown fish, angel fish, clams and anemones, that make a healthy living reef so beautiful and exciting to dive.  

With our wide variety of quality sites at over 30 different reef locations, we choose the best three sites of the day according to weather and tidal conditions. We use of a dedicated dive tender for drift dives.   All dives are guided at no extra charge and your Dive Master will brief you on the sites, equipment and safety procedures. 

Introductory Diving
No experience is required to enjoy the thrill of scuba diving under the safe control and supervision of our highly qualified instructors. Small groups ensure personal service and individual attention.

As an introductory or first time diver, there’s the choice to do an introductory dive at each of the 3 reef sites we visit on the day so you can experience 3 completely different reef environments. Or choose to spend part of your day diving and the rest snorkelling. There’s plenty of time to enjoy both activities!

After completing the necessary paper work which includes a medical questionnaire, you’ll do a briefing and tuition with your instructor onboard. Then it’s time to gear up and test your new skills on the vessel’s dive platform before heading off on your underwater adventure with your instructor. 

A cruise with Poseidon is all about having the opportunity to explore the magnificent coral gardens of the Agincourt ribbon reefs. Discover the vibrant fish life and delicate coral of three specifically chosen sites suited for conditions on the day of travel. The shallow reef lagoons are a great opportunity to see the Great Barrier Reef at its best, as some of the best coral growth is found in the shallower waters where sunlight is plentiful. For more experienced snorkellers, you’ll be thrilled with exploring spectacular drop-offs and coral pinnacles.

If you haven’t snorkelled before our crew will be on hand to give you instruction but we do recommend the ability to swim and a fairly good fitness level as snorkelling can be a strenuous activity.

The Reef Interpretation Talk and guided snorkel tour will give you an amazing insight about the reef and its inhabitants to help you truly appreciate what you are seeing.

Join the Marine Biologist for a guided snorkel tour over the shallow coral gardens, pointing out fish and marine life, corals and areas of interest along the way.

Our dedicated snorkel crew will provide you with

  • Snorkelling equipment and floatation devices.
  • Tips of technique and help for beginners.
  • In-water assistance and guidance to where the best areas to snorkel are.
  • A briefing on the biology and history of the reef.

Scuba Diving Conditions
Flying after diving: A wait of 12 hours is recommended but preferably 24 hours, if doing multiple dives, before ascending to an altitude of 300 metres or greater.
Minimum age for diving in Queensland is 12 years.
Certified divers must posses an internationally recognized SCUBA certificate card.

The Great Barrier Reef
The Great Barrier Reef is one of the world’s most amazing and unique natural spectacles. Visible from outer space, this 348,000 km2 Natural Wonder of the World is a must for everyone to experience. It extends for some 2,300 kms along the north eastern coast of Queensland, Australia, to Bundaberg in the south. To put it in perspective it covers an area about the size of the United Kingdom or the length of the entire Japanese Island chain.

The Agincourt Ribbon Reefs where Poseidon operates are 70km North East of Port Douglas and are long narrow reefs located along the very Outer Edge of the Great Barrier Reef. Being some of the most pristine areas of the entire Great Barrier Reef they are home to thriving coral gardens, a huge variety of marine life and some of the best reef snorkelling and diving opportunities in the world.

Staying in Cairns?  
It is possible to do this daytrip if you are staying in Cairns.  Return transfers Cairns accommodation transfers are available at an additional cost.  Please have your hotel name ready when booking.

Please check-in at the Poseidon/Quicksilver reservations counter inside the Port Douglas Crystalbrook Superyacht Marina between 7:30 and 8:00am. Poseidon departs the marina at 8:30am.