Kas (pronounced Carsh) is a delightful city in the very South (Mediterranean) of Turkey. It also only has a very tiny beach, less than 10 metres wide. However it does have wonderful rock shelves for sea bathing. These are populated by cafes and restaurant who provide free loungers. In return you are expected (but not obliged) to buy drinks etc from them.
The town has many decent hotels and restaurants and is a centre for activity holidays.
Kas is a small town, and you can walk anywhere within 10 minutes. Scooters are available for rent around town (30-35 YTL per day, depending on season), if you just can't be bothered.
Within reasonable driving distance are locations for Canyoning, Sea kayaking, cycling, walking, paragliding as well as wonderful beaches. Local tour companies are happy to arrange any of these activities.
Kas is the place to buy tourist kitsch. It has endless varieties, often of higher quality than most tourist towns, but most importantly, strict regulations the local government has placed on its market mean the shop owners are simply not allowed to hassle you. Complaints about a shop owner can result in the loss of their operating license.
Restaurant prices are a bit steep in Kas, but most you'll get your money's worth at most restaurants, as the food is usually excellent. Pop prices are exorbitant though, as most restaurants charge 3 YTL for a can, compared to a bottle of water for a mere 2 YTL.
Bars are plentiful, expect to pay at least 5 YTL for a drink.
The nearby "sunken city" of Kekova is a great daytrip. Bougainville Travel also offers sea kayaking at Kekova. (60 YTL per person, including transfer from Kas).