Medano Beach is the main swimming beach in Cabo San Lucas, a curving arc of sand along the Gulf side of the marina that is the only beach in town with calm, swimmable water. The Pacific-facing beaches are too rough for safe swimming, so this two-kilometre stretch carries all the beach-resort business: sun loungers, jet skis, banana boats, cold-beer vendors, and beach bars that crank up the music from midmorning.
The beach is public and free to use, though the sun-lounger operations in front of the hotels require a minimum drink or food purchase. If you walk to the northern end, away from the resort hotels, you will find it gradually quieter and emptier. The water is warm most of the year — sea surface temperatures rarely drop below 21°C even in winter — and visibility for snorkelling is reasonable close to the rocky outcrops at the northern end of the bay. The drawback of Medano is that it is rarely quiet, even in the low season. If peace is what you want, take a water taxi to Playa del Amor at the arch instead.