There are 6 different spots to dive here.
Most popular site is the Messerschmitt wreck which is for advanced or higher level divers.
St. George is the second most popular choice and the site has 2 parts to dive to. Most of the dive site is like a wall. Shallow part is recommended for all levels and if the dive guide decides it is safe there is a small cave to enter with the group. The deeper part of the site reaches 19 meters depth and there are some interesting areas with caverns and inlets on the wall.
Typical sea life to see in every dive site includes the dusky and striped Groupers, moray eel, octopus, scorpion fish and fireworms. The last years also we get to see a lot of lion fish and yellowspotted puffers that are species from the Red sea.
Rarely we see Amber Jacks, Spyraena and Turtles
April to November is the season, April being the most cold water temperatures, around 18 degrees.
May and September are recommended for the best diving conditions.
April and October are nice if you are not getting cold easily and there are chanced to see some nudibranch.
To get to Hersonissos is easy, it is just 20 km away from the main airport of the island Crete. There are many charter flights during the season that fly directly to the island, otherwise you have to go through Athens the capital city of Greece or take the ferry that leaves daily from the main port of Athens, Pireas.
This page wouldn't be possible without contributions from the following PADI members: Heraklion Diving Center. Disclaimer