The National Aquarium in Napier could become a centre for marine research.
The proposal is being led by local authorities with government backing.
Economic Development Minister Steven Joyce says it has the potential to boost jobs and growth.
"What is envisaged is a world-class aquarium that is both a visitor attraction and a conservation-focused research hub," he said on Wednesday.
"It's a very big project that would require central and local government plus the private sector all getting in behind it."
The proposed expansion includes creating the largest and deepest research display tanks in New Zealand, with a submersible lift to take visitors under water.
"Living laboratories" would allow scientists to study marine and fresh water ecosystems.
The proposal is part of the Hawke's Bay Regional Economic Development Strategy, unveiled by the Government on Wednesday.
Mr Joyce says the Government will put $50,000 into a feasibility study.