Saklikent, meaning "hidden city" in Turkish, is around 50km from Fethiye in the Mugla province, and just a 20-30 minute drive from Kalkan. It is 18km long and 300m deep; one of the deepest canyons in the world. It was opened to the public as a national park in 1996 and it has since proven very popular with tourists. There is an entrance fee per person.
You can visit all year round, though between November and March, the water can get very high, so you would not be able to gain entry to walk through. From April onwards, when most of the snow from the Taurus Mountains has melted and passed through the gorge, around 4km of the gorge is usually walkable.
When you walk over the bridge to the entrance, the first thing that strikes you is the huge, 10 metre crevice in the rock. Then the vast sculpted walls towering high above and the sound of water rushing through the ravines. There is just one obstacle before you can walk through the gorge, and that is crossing the river. The fresh mountain water is notably cold and is often up to waist height over this 6-8 metre stretch of river, so be sure to wear clothes you don't mind getting wet. Sensible submersible shoes with grips are essential as the stones beneath the water can get quite slippery. Sea shoes are ideal but if you don't have any, jelly shoes can be hired at the entrance for a small fee, although may not be as comfortable as your own.
The water is very shallow in parts but deeper in others (not normally above the knee), depending on what time of year you visit. The gorge walls create all sorts of shapes as you look ahead of you, and if you have a camera, you will find plenty of photo opportunities on the way through. After you have walked for around 40 minutes, you will come to a waterfall, and if you want to go on further, prepare to get wet again!
When you have finished walking through the gorge, you can take a leisurely wander around the little shops lining the riverside, selling novelty gifts, honey, jewellery etc. Across the other side is a cafe/restaurant and there are platforms above the water where you can relax with a Turkish tea, Efes or an ice cream and dip your feet in the cool water.