
Derby Park
Sefton's largest play area sits in a Victorian park ten minutes' walk from Bootle town centre, with a zip wire, two ball courts and statues to be climbed on and told off for climbing on.
2 places in Bootle, Merseyside, 1 of which cost nothing. Everything below is within easy reach if you live locally.
Bootle earns its page on the flume, the only one in this part of Sefton and the reason to drive here instead of defaulting to Southport. The leisure centre also has a 25 metre main pool with a moveable floor, so the depth changes to suit the session, at £7.30 for adults and £4.70 for juniors.
Then walk ten minutes into Derby Park, where Sefton's largest play area sits inside a Victorian park that opened in 1895 and has had over £750,000 spent on it, all free. Two venues, one decent half day.

Sefton's largest play area sits in a Victorian park ten minutes' walk from Bootle town centre, with a zip wire, two ball courts and statues to be climbed on and told off for climbing on.

There is a flume, and it is the only pool in this part of Sefton with one. Alongside it, a 25 metre main pool with a moveable floor, so the depth changes to suit the session.
Not in Bootle, but close enough for a day out.

Free, indoors and better than it sounds: interactive science aimed at younger children, glassblowing demos, a picnic area and a small playground outside.

St Helens' biggest park. Play areas, open space and a walled garden, and it costs nothing.

A 20-metre white head rising out of a reclaimed colliery, with woodland trails around it. Genuinely strange and memorable for kids, and a short walk rather than a hike.

A green corridor of canal towpath and parkland running from St Helens down towards Warrington. Flat, traffic-free and ideal if the bikes or scooters are coming.

Family nature sessions running through August at two St Helens parks. Pitched at exactly this age group.

Funded holiday clubs with food included, ages 4 to 18, for families on benefits-related free school meals. Worth a look even if you assume you won't qualify.

Space World in Prescot, Sensory Hive in Whiston and Boomerang: the council-listed indoor options when it rains and everyone is climbing the walls.

Soft play with a full role-play village attached, which is the bit that holds a four-year-old's attention long after the frame stops being interesting.