Exploris aquarium in Portaferry will once again welcome visitors, having been closed for almost two years.
The popular Co Down attraction had been threatened with closure over running cost concerns.
However, in February, a £2m investment was agreed that would secure the future of Northern Ireland's only aquarium, with funding coming from the Department of Agriculture, Environment and Rural Affairs (DAERA) and Ards and North Down Borough Council.
Crumlin Road Gaol Ltd are to take over the running of the attraction, which will boast many new features, including a reptile house with a Nile crocodile.
Enclosures have also been updated to accommodate a range of new fish and other aquatic species.
Visiting the site ahead of the re-launch, DAERA Minister Michelle McIlveen said, "I was impressed by the high quality attraction it has now become, while retaining at its core an educational experience. There is something for visitors of all ages".