There are places to stop and drink untill you reach the end of icmeler beach, then for a shortish distance you have to walk up a side road at the back of one of the Hotels cant remember the name. There are no bars there, but would prob take about 20 mins before you are back onto the beginning Marmaris beach where the bars start again. We did walked back from Marmaris last year. But stupidly did it at the wrong time it was 2 in the afternoon and bakeing hot, had to get in the sea for abit to cool down. We didnt quite make it got to just after the hotel where the bars stop and pursuaded a man with a speed boat to take us back he charged us 10 lira. I would say it would porb take you an hour and half to get into centre of marmaris.
Steve