Blokweer Molen

There is also the pumping station Wisboomgemaal (steam from 1868; electric from 1924 to 1996) which has the two electric motors from its second incarnation, a couple of games (the best is for 1-6 players on making sure windmills point in the right direction and aren't spinning too much because of a storm or draining too much water), wall displays (some curiously high up given the age group they seem to be aimed at), and a small shop.

Two of the windmills can be visited inside. One is an older design than the other windmills on the site, with more that would rotate, but you are limited to the ground floor and a fire in 1997 means that much of what you see of the building is a modern reconstruction. The other allows access to all but the very top, and you can see the whole mechanism, from gears driven by the sails to the curved blades that lift the water up a few metres. On busy days, you will have to wait to have the space to do so: there is not much, and part of the attraction is wondering how a large family - one per windmill - is managed.
The first windmill has a barge outside (as of 2022) with three very short films on the system. It also has a very low roof and several low beams, so be prepared to duck when moving about.
If you have mobility issues, none of these are likely to be accessible.
At the visitor centre end, paying visitors can access the roof, which gives a slightly better view of the landscape (drones are specifically banned from the site).
Another building has a six-screen film in Dutch, sometimes subtitled in English, on the area. Sit in the middle and be prepared to look at both of the larger screens at opposite ends of the room at once, as the other four can be ignored most of the time.
There are two short boat trip routes: one stops at the open windmills allowing you to hop on and off, the other just goes to the end of the line of them and back without stopping. Both run about every 30 minutes.