Not too strenuous and fun for a half day, we took the Ottogar / Dolmus bus from Kalkan, cheapest way, but check first on schedule
You can taxi as well if you want. No need for guides or to book with anyone, just show up pay and do it on your own. Now about payment, no credit cards and no Euro taken. Go with Turkish Lira, July 2019 is was 8tl for adults and 4tl students/ kids, very affordable. Also, take water shoes, water socks, decent sandals you do not mind getting wet. You will only be in water up to you mid thigh, depending on your height. No gad checks, so waterproof bags are a good idea for phones, etc, there are merchants selling waterproof pouches to wear around your neck if you wish, many people were buying them. We used common plastic bags and my back pack and had no issues. Rental shoes are available and also for purchase, 4tl to buy and 3tl to rent. Food and drinks available decent enough selection, no need to pack a lunch, we were there for four hours due to bus schedule and that was enough time certainly if you are walking in all the way. About one hour travel time by bus each way via Kalkan. We were caught without lira for the day and managed to find someone to convert euros with. Also did not notice the pay as you go, literally at the Ottogar washroom, guy not impressed I had no lira and both myself and daughter really had to go, skipped out and pretty sure was being cursed at in a Turkish. We know better now. Last note the cold part in the water is very short and worth it, about 50m, after that the water temp is very tolerable.
