We were in the Park during the low season. The price is to high for what you get. 17.50 euro for 1 adult and also a 3 year old child have to pay which is unusable in Europe. plus you have to pay more than 6 euro for the parking place.
What do you get for the price? A parking place. Nearly the half of the outdoor attraction were closed cause of the low season. So at the end there is a small sea lion pool, a whale "house", a nicely done pirates playground, a film from the 90's with subtitle, a relatively small aquareef aquarium, an exhibition about the massive plan to secure netherland during heavy storms.
The best and most impressive part was the possibilty to see part of the "deltapark".
I had the feeling that they try to mix education and fun in one place which was not done perfect. It's not bad, but there is room for improvement.
I guess the summertime is better to visit the park, cause of the more outdoor attractions. Neverthless we as a family spent more than 4 hours there including lunch.