Another great place to visit during your stay in Crete and especially with your children is CretAquarium - Thalassocosmos.
A 5000 square metre structure, it is both a research centre (housing the Institute of Marine Biology & Genetics and the Institute of Oceanography) and a fun, impressive aquarium with 60 tanks (representing interesting underwater Cretan sea landscapes) and over 100 viewing points.
2500 organisms of 200 Mediterranean marine species, from hunter sharks to lobsters, to colourful jellyfish.
Audio devices provide information in 9 languages. 15 km east of Heraklion, within what was the American base of Gournes (there are buses to it from the centre of town).
Open 365 days/year (including public holidays), Monday to Sunday: 09:30 - 21:00 (1st May to 30th September) and 9.30-17:00 (1st October to 30th April).
Admission: 9.00 euros adults, 6.00 euros 5-17 year olds & students. Children under 5 years: free. Personal audio guide: 3.00 euro.
Parking, cafe/restaurant with sea view, souvenir shop.
Tel: 2810-337788, 2810-337888.