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Baltimore Marshlands: National Aquarium’s Ambitious Plan for 2024

Baltimore marshland exhibit rendering. Design by Ayers Saint Gross; Original Concept Design by Studio Gang Architects
Source: National Aquarium

Hundreds of years ago, Baltimore’s Inner Harbor was a thriving tidal marshland teeming with life. However, over time, industrialization and urban development transformed the landscape, erasing this once-vibrant ecosystem. Now, the National Aquarium in Baltimore is on a mission to bring back the marshlands and restore the natural balance to the Inner Harbor. Through the creation of floating wetlands, they aim to improve water quality, attract native species, and educate visitors about the importance of wetland ecosystems.

The History of Baltimore’s Inner Harbor

Marsh near Easton on Maryland's rural Eastern Shore, with ducks swimming in water
Marsh near Easton, Maryland. Baltimore’s saltwater marshland would have looked similar before development.
Source: Library of Congress, Carol Highsmith Collection

Before Baltimore became a major industrial city, the Inner Harbor was a beautiful tidal salt marsh surrounded by forests. This marshland acted as a natural filter, cleaning the water before it flowed into the Patapsco River, Chesapeake Bay, and eventually the Atlantic Ocean. However, as the city grew, the Baltimore marshlands were dredged out, and the soil was paved over, leading to the deterioration of water quality and loss of habitat for many species.

The National Aquarium’s Floating Wetland Project

A computer rendering of one of the prototypes of the floating Baltimore marshlands in the Inner Harbor
A 2017 rendering of a harbor wetland prototype
Source: Facebook / National Aquarium

Prototype Development and Lessons Learned

The National Aquarium embarked on a journey to recreate the marshlands by developing floating wetland prototypes. These prototypes served as learning experiences, allowing the team to refine their designs and overcome challenges. One of the key lessons learned was the importance of stability and resilience in large-scale floating wetlands. Previous small-scale prototypes had encountered issues with maintenance and imbalance, leading to their failure.

A serene setting by the water featuring a small island manmade island that serves as a floating wetland with shrubbery and two ducks resting by the edge, with sunlight reflecting off the surface of the water.

The conditions of the inner harbor also proved challenging to sustaining aquatic life, with periodic low oxygen levels due to algae blooms making it difficult for animals to survive. Using techniques from aquarium habitats, the team added oxygen to the wetland habitat’s waters. Beyond the physical resilience of the structure, this provided resilience to the water around the wetlands in order to sustain a thriving ecosystem in periods of low oxygen levels.

View of Kenilworth Aquatic Gardens marshland from the boardwalk
View of Kenilworth Aquatic Gardens marshland from the boardwalk, showing a channel through the marshland

In DC, we’re lucky to have some marshlands still intact on the Anacostia, like at Kenilworth Aquatic Gardens. If you go to Kenilworth, you’ll see that there are some natural channels of water. In Baltimore, in their later prototypes, they wanted to add those waterways to provide an experience that was closer to nature. When they did add those waterways, they saw that blue crab came within 48 hours to molt there. This was a testament to their efforts.

Environmental Benefits of Floating Wetlands

A night heron fishing for Atlantic silversides on the floating marshland in Baltimore Harbor
A night heron fishing for Atlantic silversides on the floating wetlands in the Baltimore Harbor
Source: Facebook / National Aquarium

The introduction of floating wetlands in the Inner Harbor offers numerous environmental benefits. These man-made wetland “islands” act as natural filters, absorbing excess nutrients and pollutants from the water. They also provide habitat for a variety of species, serving as nurseries for fish, safe spaces for blue crabs to molt, and feeding grounds for wading birds. By improving water quality and supporting native wildlife, the floating wetlands contribute to the overall health and resilience of the Chesapeake Bay ecosystem.

The Harbor Wetland Exhibit

Realistic rendering of the harbor wetland exhibit at Baltimore Aquarium, showing the bridge onto the exhibit
Design by Ayers Saint Gross; Original Concept Design by Studio Gang Architects
Source: National Aquarium

Building upon the success of the prototypes, the National Aquarium is now working on the Harbor Wetland exhibit. This exhibit will cover a quarter-acre of the Inner Harbor between Piers 3 and 4. It will feature a 15,000 square foot floating wetland habitat designed to attract native species such as blue crabs, American eels, Eastern oysters, and night herons. The exhibit aims to recreate the natural salt marsh habitat that once thrived in Baltimore City, providing a glimpse into the pre-industrial history of the area.

How Much Will the Baltimore Marshland Exhibit Cost?

Visitors will be able to access the Harbor Wetlands for free. While there is an entrance fee for the National Aquarium, they have decided to make the Baltimore marshlands free to access for all visitors.

When Will the Harbor Marshlands Open?

A bright, clear day at a waterfront with a view of the Baltimore Aquarium's architectural geometric glass façade and a floating dock system in the foreground, set against a backdrop of a calm harbor. The floating dock system is bare, and being installed as part of their wetland exhibit.
Wetlands exhibit under construction

The exhibit is set to open in 2024, and will be a top thing to do in Baltimore when it does. However, as with every new project, this date may change if there are any delays in construction or implementation. Check the National Aquarium website for updates.

What Will the Baltimore Marshlands Be Like?

One of the primary goals of the National Aquarium’s Harbor Wetland exhibit is to educate and inspire visitors about wetland ecosystems and their significance. Through interactive displays, educational programs, and guided tours, the aquarium aims to raise awareness about the importance of wetlands for clean water, biodiversity, and climate resilience. By engaging visitors of all ages, the National Aquarium hopes to foster a sense of stewardship and encourage individuals to take action in their own communities.


The revival of Baltimore’s marshlands is a testament to the power of restoration and the importance of preserving natural ecosystems. Through the National Aquarium’s innovative floating wetland project, the Inner Harbor is being transformed into a thriving habitat once again. The Harbor Wetland exhibit will not only serve as a reminder of Baltimore’s pre-industrial history but also inspire visitors to appreciate and protect the invaluable wetland ecosystems. With ongoing efforts to restore marshlands and educate the public, Baltimore is paving the way for a greener and more sustainable future.

Valerie Moore

Having lived in Washington, DC for the past 16 years, Valerie has a lot of thoughts about the best things to do, eat, and know around the city. She loves doing deep dives into the interesting things she finds, and sharing with the world. You'll often find her dog, Lil Mikey, along for the ride.

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