Officials at Seattle Aquarium are looking into the possibility of a grand expansion, adding at least 40 per cent more exhibit space to the visitor attraction at a cost of up to US$200m (€178.5m, £127.1m)

The expanded aquarium would be able to handle around double the number of visitors at the attraction, increasing annual capacity to around 1.6 million people, with the proposed expansion stretching out across the Seattle waterfront.

The highlight of the plans is the Tropical Pacific pavilion building, which will be a prominent feature of the aquarium and will connect the waterfront with the nearby Pike Place Market, as well as see the addition of a large shark tank. Other features include two new exhibits both based on the waters surrounding Washington.

"We are at capacity now on many busy weekends," said aquarium president and CEO Bob Davidson. "[The City Council] is projecting double the number of people on the waterfront after the viaduct (an elevated highway due to be demolished) comes down."

The city has committed US$45m (€40.1m, £28.6m) towards the development as part of its Central Waterfront Project. Officials at the aquarium are looking to raise at least the equivalent amount, if not more, and have brought in Chicago-based Campbell & Co to help devise a fundraising campaign.

At present, no cost has been set for the expansion, though the figure is thought to be between US$90m (€80.3m, £57.2m) on the low-end and US$200m on the high-end. No plans have been drawn up yet, but Marc L’Italien of San Francisco-based architecture firm EHDD has been named as masterplanner for the development.

City Council members have already been briefed on the aquarium’s expansion plans, with a final plan to be presented at a public meeting in July before being submitted to the City Council for final approval. If plans go ahead, construction will begin in 2019 and be completed in 2021.