Simplify the following text for a Grade 11 native English-speaking person.
Original: A popular United Kingdom indoor waterpark is the Sandcastle Waterworld at Blackpool , England which has the Master Blaster , the world 's longest indoor roller coaster-style ride .
Simplified: The premier UK indoor waterpark is the Sandcastle Waterworld at Blackpool , England which has the Master Blaster , the world 's longest indoor roller coaster-style ride .