Harbor Wetland

Immerse yourself in a re-created salt marsh habitat like those that existed in Baltimore City hundreds of years ago.

Coming Soon

Opening in 2024, the National Aquarium Harbor Wetland presented by CFG Bank will be a free, outdoor exhibit between Piers 3 and 4 of the National Aquarium campus on Baltimore's Inner Harbor. Please note that the images on this page are of the floating wetland prototype we installed in the Inner Harbor in 2017. These are not images of the Harbor Wetland exhibit.




square feet


grasses and shrubs

Reintroducing Salt Marsh Habitat

The Aquarium's newest exhibit will look forward by looking back. Hundreds of years ago, Baltimore's Inner Harbor was a tidal salt marsh surrounded by forests. Back then, when rain fell or snow melted, it soaked into the soil. The soil held the water, filtered it and then slowly released it. This filtered water then seeped into the harbor—part of the Patapsco River—and its tributaries before flowing into the Chesapeake Bay and the Atlantic Ocean beyond. This natural process helped keep these waterways clean and healthy.

As the city grew, thanks to the natural resources provided by its streams and rivers, the harbor was dredged out, the soil was paved over with asphalt and concrete, and the forests were replaced by housing and industry.

Today, rain still falls and snow still melts, of course—but without much soil to seep into, the water instead rushes over sidewalks and roads, racing into storm drains or directly into the harbor and other waterways. All the pollutants, chemicals and trash it picks up along the way are carried with it.

By mimicking the natural salt marsh habitat that once existed in Baltimore City, Harbor Wetland is reintroducing an important ecosystem. In the process, it provides green infrastructure that promotes healthy water; attracts native species like blue crabs, American eels, Eastern oysters and night herons; and teaches students and guests about wetland ecosystems.

Baltimore's Inner Harbor is teeming with life, and it can be restored. Immerse yourself in Harbor Wetland and see how you can be part of the harbor's next chapter!

Spotlight on Cordgrass

Cordgrass is a workhorse of the saltmarsh ecosystem. The roots help stabilize sandy soil and the plants absorb carbon. These grasses also provide essential habitat for a variety of species, both when it's submerged during high tides and exposed during low tides. Algae grow on the stems and are grazed upon by periwinkle snails during low tide; these snails, in turn, are eaten by fishes during high tide, when the grass is completely submerged. The plants also offer protection for small prey, like juvenile blue crabs. They hide among the thick stems, protected from larger predators that can't maneuver the tight spaces.

On the floating islands of the Harbor Wetland exhibit, cordgrass and other native grasses and shrubs serve another important function—removing excess nitrogen from the harbor. Because the plants are growing hydroponically, in a soil-less material similar to a giant floating Brillo pad, their roots take up nutrients directly from the water.

Excess nitrogen in the harbor—which comes from polluted stormwater runoff and Baltimore's aging sewage and stormwater systems—fuels algal and bacterial blooms that harm fishes, turtles, crabs, birds and other animals.

Support This Work

You can help shape the Inner Harbor's next chapter!

Beyond keeping a careful record of all the wildlife seen on and around the floating wetland prototype, the National Aquarium team partners with researchers to analyze biofilm—structured mats of bacteria—from the harbor and conduct DNA barcoding. This allows us to identify species that aren't as easy to see and learn more about the Inner Harbor's biodiversity.

Fourth's a Charm

In 2010, the National Aquarium installed a 200-square-foot floating wetland in Baltimore's Inner Harbor. This was the first time this technology was introduced into a brackish tidal system in the United States. Prior to our initial efforts, floating wetlands were traditionally used in stormwater retention ponds.

Since that time, the Aquarium's Conservation team has refined the floating wetland design to develop a model that best fits the specific needs of the Inner Harbor, evaluating its progress through scientific research. The fourth prototype, installed in 2017, is the model being replicated on a large scale for Harbor Wetland.

This is our BLUEprint

Several years ago, we created a vision to evolve into an aquarium of the 21st century, one that inspires the next generation of conservationists. Three keystone projects form the foundation of this vision, which we call our BLUEprint—the Animal Care and Rescue Center, Dolphin Sanctuary, and National Aquarium Harbor Wetland presented by CFG Bank.

Presented By

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