Its an old thread admittedly but some things to add here.
For sunsets try Keri lighthouse or Kampi on the south west coast.
Others have already mentioned shipwreck - the isignature photo of the island. It looks FAR nicer from the 600ft cliff and viewing area than it does up close. Up close you see it for what it is - a rusty sharp piece of metal and tetanus waiting to happen.
Limnionas bay is a fabulous scenic place for photos (cliffs leading into sea etc) plus lovely for a spot of lunch as is Porto Vromi a bit further North.
Due to the layout of the island the entire west coast consists of tall white cliffs dropping into clear blue sea so if its that sort of landscape you want, that's where to go.
Also don't forget inland. In the mountains you can have a great view to the plateau and other resorts and due to the size can see the entire island and often across to the mainland.
Zakynthos town is nice at night around the main square area for some buildings/people type shots.
Another lovely place to visit and shoot is Agios Nikolaos in the north east. Again a quiet bay surrounded by cliffs, carrying on north from there to the lighthouse (Skinari) where you again have layered rock leading into the sea and very clear views of kefalonia. Its worth a drive up the road on the east coast that goes through town, Tsilivi, Alykes and the other resorts as you get some good high views where it cuts the mountains. Some nice bays there too.
As for underwater life, it depends what you're used to. Being Greece they have dynamited/spearfished most things plate size. There are things like striped bream and so on. If you go snorkelling around somewhere like Dafni you'll see some of that. Failing that most of the diving locations are around the south west Keri peninsula where you'll see bit more. Very clear water but little life.
Turtles generally you'll see most in June into July and then the numbers slowly go down. By September you'll be lucky to see any. You need a boat trip for that really (there are loads from Laganas/Kalamaki and once one is spotted about 30 boats arrive). Unlikely to see them on the beach as they only come to nest and beaches are off limits during the darkness hours.
To see these places you really need to hire a car. The tourist trips just wont do it or get you there without 4000 other people. Its a small island and you can be anywhere on it within about 45 mins.
Some GPS/Google earth things:
Shipwreck viewing: 37°51'43.46"N 20°37'31.92"E
Porto Vromi: 37°49'19.26"N 20°38'0.47"E
Kampi: 37°46'57.16"N 20°40'48.57"E
Limnionas: 37°45'11.51"N 20°41'42.49"E
Keri Lighthouse: 37°39'18.11"N 20°48'26.30"E
Town viewpoint: 37°47'16.87"N 20°53'18.06"E
Agios Nikolaos (the one in the north not the south): 37°54'26.34"N 20°42'19.31"E
Skinari lighthouse: 37°55'58.13"N 20°42'1.55"E
Others:
Don't miss it !! Go in the week - much quieter
