A 170,000sq ft (51,816sq m) vertical aquarium is one of the ideas being considered for a proposed 500ft-high (152m) observation tower at the centre of a development project on the California coast at San Diego.

Seaport San Diego, a US$2.4bn (€2.15bn, £1.93bn) scheme that encompasses 70 acres of land and water along Harbor Drive, is currently in the initial planning stages with developers 1HWY1 and architects Bjarke Ingels Group (BIG).

The vertical aquarium, which would span the entire height of the tower, and would emulate the varying depths of the ocean, is just one of several ideas being floated for the tower. Others include a butterfly exhibit, a high level scrambling net, a wind garden, and an outdoor auditorium for basking in the clouds.

The lower levels of the tower would house hotels, retail and F&B.

Designed by BIG, the tower is intended to be an internationally iconic piece of architecture for San Diego – something many feel the city currently lacks. Its design is eye-catching: a cylindrical tower with an hourglass figure, centring around what appears to be a stack of spinning discs, evoking different images and impressions at varying elevations and vantage points.

Someone on the ground looking up might view the tower as a cascading hanging garden, while a viewer at the top could look out at the horizon and have a sensation of floating above the clouds.

Seaport San Diego is intended as a "thoughtful and creative reimagining" of a key part of the San Diego waterfront. Included in the vision are parks, a plaza, an urban beach and waterfront public realm.

There are a number of hurdles to overcome before the tower becomes a reality. One of these could be the 1976 Coastal Act, which limits most coastal zones in California to a 30ft height restriction. Downtown San Diego is, however, exempt from this restriction.

The project and its environmental impact report, which is yet to be completed, must first be approved by the Port of San Diego, after which the Coastal Commission must also rubber-stamp the project.

A report in the San Diego Union Tribune suggested there is some opposition to the scheme, with San Diego coastal planner Melody Lasiter saying: "We have concerns about the bulk and scale of the project in general."

She added that the tower's height, the width of the base and its location on the promenade were all problematic.

However, others believe a solution will be found, including environmental consultant Allison Rolfe, who said: "We won't figure out how to get a win-win until the very end."

Seaport San Diego is not the only major development project in the pipeline for the Port of San Diego. There's also a US$1bn bayfront regeneration project in the pipeline that includes a new luxury hotel, convention centre and two public parks. The development – at Chula Vista – has 275,000sq ft (83,820sq m) of space for restaurants, bars, a swimming pool and lazy river.