Salvage of the Iconic Underwater Observatory at Green Island

North Marine is engaged to salvage the 1954 underwater observatory from Green Island on the Great Barrier Reef and tow it to the Port of Cairns in Queensland.

Client: Quicksilver Group – Great Adventures

Scope of Work

North Marine was contracted to Project Manage this complex operation. It included salvaging the structure from the ocean floor, transporting it to Cairns by barge and overseeing demolition.

The experienced commercial diving department at North Marine successfully executed the salvage and removal of the submerged observatory, located at Green Island out of Cairns.

North Marine’s divers excavated the partially-buried underwater structure, following complex environmental planning and stakeholder consultations.

The observatory was then towed onboard a barge to the mainland, where historic parts of the structure were retained by Great Adventures staff prior to demolition.

In situ since 1954, underwater dredging was required to dislodge the 38-ton-weight. It was floated by lift bags, maneuvered and lifted by crane onto a barge for towage to the mainland.

Divers then cleared 2 tons of debris from the site, including 44-gallon drums & steel railway track ‘weights’.

North Marine successfully completed the contract with all project objectives delivered in full. The best outcome was achieved for the client.

A Key Piece of Queensland Tourism History

It is with a sad heart and happy memories that North Marine undertook the massive task of deconstruction and marine salvage of the iconic 1954 Underwater Observatory at Green Island.


  • Local SME business using a local FNQ workforce

  • Established operating within environmental controls of the Great Barrier Reef Marine Park

  • ISO accredited. Applicable insurance to complete works

  • Adept at delivering logistically complex & remote projects

  • A fleet of suitable charter vessels to perform works

  • Experienced project managers and key personnel

  • Established co-ordinating with stakeholders & contractors


North Marine successfully completed the contract with all project objectives delivered in full.

The best outcome was achieved for the client.

Download Case Study

About the Green Island Underwater Observatory

The underwater observatory at Green Island was the brainchild of Vince Vlassoff, a 37-year-old Australian-born Engineer, and Lloyd Grigg after they met on a crocodile safari cruise operated by Vlassoff.

Before snorkelling or scuba diving had become mainstream activities, this pioneering piece of architecture truly was a revolution in reef tourism, which up until this point had largely been occasional ferry trips taking people to offshore islands for a day trip. Never before had the general visitor had access to freely view the Great Barrier Reef beneath the surface.

The entrepreneurial pair imagined an underwater theatre, unlike anything ever constructed of its kind before. They envisioned a place where the public could venture beneath the waves to a chamber of windows, whereby they could witness the marvellous fish, coral, and aquatic life to be seen.

Construction of the chamber began in 1951 and took twelve months from planning to final submersion – an incredible time frame considering the challenge of the task and all the unknown factors.

For nearly 60 years, the underwater observatory delighted visitors and provided a means of viewing the incredible underwater world.


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