Datça is located 70-80 km west of [wiki=467b8080ff984c4303e4687b6a4de053]Marmaris[/wiki]. The road from Marmaris (road number: D400) is the only way to arrive overland.
Although it’s possible to find direct bus services from main centres of the country, such as [wiki=0ef8f876d62a45352e28410454e3634b]Istanbul[/wiki] during summer months; in the rest of the year your best bet is to arrive at [wiki=467b8080ff984c4303e4687b6a4de053]Marmaris[/wiki] first, then transfer to another bus bound for Datça there.
There are ferries from [wiki=53537948ccf2d741c5c1374c5c72535a]Bodrum[/wiki], arriving at the port on the northern coast of the peninsula. From there, Datça -which is on the southern coast of the peninsula- is a 10-15 minutes drive away.