During the aquarium's early years, planners considered ways in which it could be used as a foundation for additional public projects with aquatic themes.
In 1988 it was suggested that it could become the anchor of a complex that would also include a sports fishing trade center, potentially making Chattanooga the sports fishing capital of America.
In 1993 SITE, one of the firms which had designed Ross's Landing Park, was asked by regional development authorities to design a center for exploration of other aspects of aquatic science and activity; its proposal, the "Aquatorium," included a museum, a conference center, and a spa.
Neither of these ideas was developed.

In 1995 the aquarium broke ground on a $14 million IMAX center on land adjacent to Ross's Landing Park, containing an educational facility and offices as well as the IMAX theater.
This expansion opened in 1996.
During its first decade the aquarium also focused on improving and refining its initial designs for the permanent exhibits, and presented two temporary exhibitions, "Jellies: Phantoms of the Deep" in 1998 and "VENOM: Striking Beauties" in 2000.

In 2002 Chattanooga undertook a new public planning process, the 21st Century Waterfront, to continue the reorientation towards the river that had begun with the Tennessee Riverpark Master Plan.
 An expansion for the aquarium was part of the resulting blueprint for $120 million in improvements to both sides of the downtown riverfront.
 Although the plan for Ocean Journey was announced a month after the developers of what would become the Georgia Aquarium in Atlanta, two hours away from Chattanooga, announced their choice of a building site, Tennessee Aquarium officials insisted that their own plans were not a response to this potential competition and that the addition of saltwater exhibits simply reflected visitor requests.
 However, by the early 2000s analysts were warning of an "aquarium glut" in the United States, after the number of accredited public aquariums in the country grew from 26 to 40 between 1993 and 2003 while the overall number of aquarium visitors rose by only 23% during a similar time frame.

The aquarium raised the $30 million needed for its expansion through a combination of a $10 million bond issue and $20 million raised as part of the 21st Century Waterfront campaign, which included private donations, federal and state funds, and the proceeds of a hotel/parking tax.
 To design the new building and exhibits, the aquarium turned to the firm of Chermayeff, Sollogub and Poole, whose principal Peter Chermayeff designed River Journey as part of Cambridge Seven Associates.
 While the building's diverse exhibits departed from the Tennessee River theme of River Journey, its structure included a multi-story glass gallery designed to maintain visitors' connection to the river.
Work began on the expansion on April 3, 2003, and Ocean Journey opened on April 29, 2005.
 The 21st Century Waterfront incorporated the new building with River Journey and Ross's Landing Park, continuing the theme of Chattanooga's early history by locating The Passage, an interactive public art installation marking the site of the beginning of the Trail of Tears in Chattanooga, alongside it.
During the aquarium's early years, planners considered ways in which it could be used as a foundation for additional public projects with aquatic themes. In 1988 it was suggested that it could become the anchor of a complex that would also include a sports fishing trade center, potentially making Chattanooga the sports fishing capital of America. In 1993 SITE, one of the firms which had designed Ross's Landing Park, was asked by regional development authorities to design a center for exploration of other aspects of aquatic science and activity; its proposal, the "Aquatorium," included a museum, a conference center, and a spa. Neither of these ideas was developed.
In 1995 the aquarium broke ground on a $14 million IMAX center on land adjacent to Ross's Landing Park, containing an educational facility and offices as well as the IMAX theater. This expansion opened in 1996. During its first decade the aquarium also focused on improving and refining its initial designs for the permanent exhibits, and presented two temporary exhibitions, "Jellies: Phantoms of the Deep" in 1998 and "VENOM: Striking Beauties" in 2000.
In 2002 Chattanooga undertook a new public planning process, the 21st Century Waterfront, to continue the reorientation towards the river that had begun with the Tennessee Riverpark Master Plan.  An expansion for the aquarium was part of the resulting blueprint for $120 million in improvements to both sides of the downtown riverfront.  Although the plan for Ocean Journey was announced a month after the developers of what would become the Georgia Aquarium in Atlanta, two hours away from Chattanooga, announced their choice of a building site, Tennessee Aquarium officials insisted that their own plans were not a response to this potential competition and that the addition of saltwater exhibits simply reflected visitor requests.  However, by the early 2000s analysts were warning of an "aquarium glut" in the United States, after the number of accredited public aquariums in the country grew from 26 to 40 between 1993 and 2003 while the overall number of aquarium visitors rose by only 23% during a similar time frame.
The aquarium raised the $30 million needed for its expansion through a combination of a $10 million bond issue and $20 million raised as part of the 21st Century Waterfront campaign, which included private donations, federal and state funds, and the proceeds of a hotel/parking tax.  To design the new building and exhibits, the aquarium turned to the firm of Chermayeff, Sollogub and Poole, whose principal Peter Chermayeff designed River Journey as part of Cambridge Seven Associates.  While the building's diverse exhibits departed from the Tennessee River theme of River Journey, its structure included a multi-story glass gallery designed to maintain visitors' connection to the river. Work began on the expansion on April 3, 2003, and Ocean Journey opened on April 29, 2005.  The 21st Century Waterfront incorporated the new building with River Journey and Ross's Landing Park, continuing the theme of Chattanooga's early history by locating The Passage, an interactive public art installation marking the site of the beginning of the Trail of Tears in Chattanooga, alongside it.
Tennessee Aquarium