The entertainment group behind Birmingham's National Sea Life Centre has been snapped up for £102.5 million.
Merlin Entertainments was bought by US private equity firm Blackstone, which is also bidding for the Legoland theme parks.
The deal for Merlin, whose attractions received more than six million visitors last year, marks a major profit for seller Hermes Private Equity after it bought the firm for £ 72 . 5 million just 15 months ago.
Poole-based Merlin runs 28 attractions in Europe under the Sea Life, Dungeons, Seal Sanctuary and Earth Explorer brands.
In the UK it has six Sea Life centres including the flagship Birmingham site, three Dungeons in London, York and Edinburgh, and Seal Sanctuaries in Cornwall, Scotland and Norfolk.
The Brindleyplace centre employs 15 full-time staff, a further 35 seasonal employees and attracts over 300,000 visitors annually. Its centrepiece attraction is an 800,000-litre tank featuring hundreds of coral reef fish and two giant sea turtles. Merlin's attractions outside the UK are in eight European countries including Germany, Finland, France and Spain.
New figures show the group increased the number of visitors by more than a million to 6.3 million last year and increased underlying earnings by 37 per cent to £14.5 million.
A spokeswoman for Blackstone said staff would remain with the group under the leadership of chief executive Nick Varney. If Blackstone is successful in its bid for Legoland from Danish owner Lego, the business is expected to be integrated into Merlin.