Schoolchildren and people with disabilities are among the visitors who will be able to enjoy a new land train at the Millennium Coastal Park in Llanelli.
The train will run throughout the year
The Sospan Hopper train will make its first nine-mile round trip on Saturday, after being officially unveiled on Friday.
Designated carriages for four wheelchairs are linked to the 64-seater train.
"Disabled people couldn't see the park in this way before because there is a path - now they can see it from the specially-built carriages," said Dave Tucker, project manager.
"There is a lot of history on the estuary, plus the wildlife.
"It's not just for the summer, it will be a success because there is a lot to see on that stretch.
"We want to extend it to the wildlife park in the other direction," he added.
The Sospan Hopper will make six trips a day, all year round, between Llanelli and Burry Port Harbour.
Five disabled people are among the staff operating the tour.
Riders will be able to hop on and off the train, while speakers relay information about historical and wildlife aspects of the park.
"One of the most interesting facts is the Bluebird was tested down here," said Mr Tucker.
"The train is geared up for schools, educational trips and the disabled, and can be used by anyone at the park," he added.
Llanelli MP Denzil Davies will officially unveil the train at 1400 GMT on Friday.
Children from Bigyn Primary and Morfa and Felinfoel Juniors will attend, as well as the Llanelli Sea Cadets who will fire a cannon.
The event will also include a fanfare by the Royal Regiment of Wales.
The coastal park, owned by Carmarthenshire County Council, was built on a landscape of dereliction and former industry.
Works on the northern shoreline of the Loughor Estuary were replaced by the £27.5m park.