A new purpose-built leisure facility in the north side of Stanborough Park.
A ground-breaking event on Wednesday 30 October marked the start of construction on the new adventure and splash play area.
Plans include a large 600m2 splash park area, with a paddling river meandering through the centre. This will be surrounded by a nautical themed adventure play area - including a large pirate ship - and a variety of other play equipment for children of all ages.
An outdoor gym and sports pitch will provide teenagers and adults with a range of new health and fitness activity options.
The refurbishment of the toilet block and a new kiosk enhances existing facilities, with the current play area being replaced with an assortment of seating and picnic spaces, more in keeping with a riverside environment.
Entrance to the park would remain free.
Splashlands is scheduled to open in 2020, coinciding with Welwyn Garden City's centenary year. Work is expected to start on site at the end of the summer season.