San Diego port commissioners on April 14 are scheduled to review six proposals to redevelop 57 acres on Harbor Island, including several sites that formerly housed rental car lots. Proposed new elements include hotels, office buildings, public plazas, an aquarium, and a high-tech golf driving range.

Unified Port of San Diego staff has recommended that two of the proposals — from locally based developers Oliver McMillan Inc. and Sunroad Enterprises – proceed to a second and final round of review. The proposals are among six finalists, winnowed from among several more submitted to the port district during the past six months.

According to a port staff report, the Oliver McMillan plan calls for a mixed-use development including two 500-700-room hotels, along with a 200-300-room “Boat-el” with affordable accommodations; canals for kayaks, paddle boards and other small water craft; a sea plane exhibit; a retail and office complex with a public market and marine services; and a network of plazas, open spaces and pier viewpoints.

Oliver McMillan would team on its project — estimated to cost between $760 million and $1.12 billion — with locally based Evans Hotels, Pacific Marina Development and Almar Management Inc.

The Sunroad proposal includes three alternatives incorporating, in various combinations, two 175-room hotels, a 150-room hotel, an urban beach, restaurants, space for harbor police and port offices, and facilities for research related to the region’s “Blue Economy.” The anticipated investment cost is between $100 million and $300 million.

Plans not recommended by port staff, but slated to be reviewed, include one by Topgolf International Inc. for a “state-of-the-art entertainment destination that blends a technology-based driving range with a full-service food and beverage operation.”

Also, Tripp Development has put forward a $2 billion proposal for an aquarium with 1,400 hotel rooms, a “sky spire” observation ride, a promenade, restaurants and retail, and an ultra-light public transportation system connecting the site to the airport.

In another proposal, locally based Pacific Coast Historical Dinner Show is seeking to develop a new performance venue.