Candarli is a sweet little resort about 1 hour's drive north of Izmir. It's really popular with people from Izmir, who have summer houses there, but not many foreigners visit at all - which could be advt or disadvt for you

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There are plans for a marina, though these have been on the table for years.
The main problem with the place is that it's very close to the huge Aliaga petro-chemical and industrial complex, which is visible across the bay - and way to close for my liking! I know about it as i was based in Izmir for 18 months and we used to go out there to visit friends. Hope that helps.