Diving and Snorkeling near Heraklion

No. Heraklion is a working city whose sights are the Venetian harbour, the Archaeological Museum and Knossos. The nearest sandy beach is Ammoudara, about 5 km west; Agia Pelagia (16 km west), Gouves (18 km east) and Hersonissos are the resort beaches. Most tours here are therefore day trips, not beach days.

Yes, but not by boat from the city. Spinalonga boats leave from Elounda, Plaka and Agios Nikolaos on the north-east coast, so from Heraklion it is a coach day trip of roughly 8 to 11 hours. If you are staying nearer Agios Nikolaos or Elounda, book the short boat trip directly.

It is possible, not relaxing. The fast ferry takes about two hours each way, and the trips listed here last 9 to 14 hours and start at around €185. If you only have a day or two for Santorini itself, stay overnight instead; if you are based on Crete, the day trip is the realistic way to see it.

No. Knossos is about 5 km south of the city centre, and a city bus takes roughly 20 minutes. A tour adds explanation, not transport: in the feed the entry-ticket listings carry 3.9 stars and the guided small-group walk 4.9. The site has little shade, so go early in summer.

Not for the city and not for Knossos. For Lasithi (about an hour to an hour and 20 minutes each way) or Matala (roughly 75 km) a car gives you freedom, but a guided day tour removes the mountain roads. We link car rental at the end of the guides, so you can compare.

You can, but both lie in western Crete. Samaria Gorge tours with Heraklion pick-up last 12 to 17.5 hours; Chania, about two hours by road to the west, is a much shorter start. If those are your main goals, consider staying in Chania instead.

In July and August the popular boat and quad slots sell out a few days ahead. Outside high season the evening before is usually fine. Since almost every tour can be cancelled free up to 24 hours before, booking early costs you nothing.