MYSTERY deepens around a series of rooms found underneath South Promenade outside Blackpool Sandcastle.
Construction workers unearthed a 20ft-deep room with a door off it under the Promenade as they prepared foundations for the attractions two new Amazon-themed rides.
Initially thought to be part of the old open air swimming pool on the Promenade, it is now thought the rooms could be something completely different.
Sandcastle manager John Child said: “It really was like something out of the TV series Lost.
“We found a grill-like hatch in the floor and then found a 20ft drop into a room below.
“We don’t now think it was part of the open air pool.
“It could be part of an air raid shelter, a storm drain, or even the pumps for a large fountain that used to be on the other side of the road.”
Investigations are under way to find out exactly what the huge void is – but so far it has stumped heritage experts.
And it is hoped that the discovery will not delay the two new slides’ installation.
Mr Child added: “We hope everything will carry on as scheduled, but it looks like we will have to dig more up to see the extent of these rooms.”
The new slide attractions have set off on a ride of their own.
This week, Canadian workers finished manufacturing the sections for the two Aztec-themed rides, and started loading them onto ships heading for Britain.
All of the pieces should be in Liverpool in around four weeks, ready for transporting to Blackpool where they will be assembled.
Mr Child added: “All of the enabling works have been done and the attraction has remained open throughout. The changing rooms for the centre have already been refurbished and the work we’ve been carrying out has no affect on the running of the Sandcastle.
“The slides are coming over on a container ship and we expect to see them in around a month.
“The Canadians are specialists in this specific type of ride so that is why they are coming from there.”
The rides are due to be installed by August 5, but last week hopes were high they could be in operation by July 23.
Now, workers face a race against time to find the extent of the mystery rooms below the Promenade.
They will most likely be filled in with concrete.