Kaş is the diving capital of Turkey. It is one of the top 100 dive sites of the world because of its abundance of marine life and ancient relics. There are over 30 dive sites, all within a 20 minute boat ride from the dock. You can wreck dive, cave dive, and explore deep canyons.
Sometimes, there are even underwater art exhibitions held here, so keep in touch with the locals to find out more information. Be sure to bring your camera, you are certain to run into some incredible sights, and probably even some sea turtles.
In Bodrum, you can do some great wreck diving. There is a massive aircraft carrier to explore, as well as several other boats. A fairly intact propeller plane is also yours to explore. Old cars, beaten by time and water damage, are like skeletons of their former selves.
Turkey is the gateway between Europe and Asia, so there are many, many ways to make your way into and through the country. Fly, take the train, or drive. Large cities have metros and buses, metered taxis, and Dolmuşes (minibuses). If you want to get farther out, take a Dolmuş or rent a car.