Isolino has a lot of camping spots, would recommend you book ahead of time.
We were there over the ascension holiday in mid May, water in the lake as well as in swimming pool and water park still cold, but we went for the water park anyway in the afternoons. The kids loved the water park.
They have 3-4 beaches and easily accessible from most parts of the camping. One long sand spot great for kids under 5 years old to play! I would say this is the most family friendly (especially for small kids) camping we have ever been. They even have a kids toilet with baby showers.
We stayed in the camping for 3 days, very relaxing. There are also hiking trails around.
Yoga, pilatus, tabata, pony riding, dancing, concert etc. programs are available.
Only negative point is the restaurant in the camping. Other than that, great camping!