On a sunny February morning, the blue-green flats of Terra Ceia Aquatic Preserve are calm, clear and shimmering with light, waters like stained glass encircling a small island that locals call “Paradise.”

From above, the island is a splotch of green brush and white sand just south of Interstate 275.

From ground level, it’s a world of its own. Tiny crabs skitter the shoreline. Oysters dangle on mangrove roots. Seabirds dive shallow waters inhabited by fish and sea turtles.

Despite its proximity to the highway, this pocket of Tampa Bay has a quiet calm that makes it feel removed from urban Florida — an atmosphere that attracts wildlife and nature-seekers.

But some worry that could soon change.

Two companies, SSA Marine and Slip Knott LLC, are proposing to build a new cruise terminal on this untouched landscape to accommodate megaships incapable of passing under the Sunshine Skyway Bridge.

The companies have pitched the preservation of Rattlesnake Key, which SSA Marine now owns, as a conservation tradeoff ahead of their plans to develop the Knott-Cowen Tract into a central hub of cruise port activity.

While details are so far slim, their plans also show Paradise Island and Skeet Key within the footprint of the project, which would require significant dredging and development in the area. The owner of nearby Ed’s Key also recently proposed developing a resort there to complement the cruise port.

But many locals want to see the entire area — including its islands, wetlands and shallow bay flats — left untouched.

Just offshore Paradise Island, a recently placed sign reflects that sentiment, reading simply: “NO CRUISE PORT.”

What could a cruise port change? Here’s a closer look at the area as it exists today.