Goa Cina beach
We found this the best beach for swimming, at least the part to the west of the "cave island". The beach gets its name from a rocky peninsula with a cave in it where Chinese people are said to come and meditate hoping for success in business.
East of the peninsula the sea bottom is rocky, at low tide villagers come to seek seafood. West of the peninsula the beach is more sandy but steep: only safe if you know how to swim.
Warning: Keep an eye on your belongings at all times! The beach being so remote, thieves may follow you when they see you going there. This we found out after Theo missed his camera he had left with his clothes for a swim. When we reported this at the police (Polsek) at Sumbermanjing Wetan, they told us: "We have four men in custody for a similar offense at the same place, evidently we have not caught them all yet." And later Theo met a man who as a student ten years earlier had camped at Goa Cina beach and was robbed too.
Directions: Leave Malang as if you were going to Sendang Biru beach, via Turen and Sumbermanjing Wetan. A few km before Sendang Biru beach there is a fork in the road. Instead of going left, go right as indicated. Follow the brand new, wide road for about 2 km, find an unpaved road to the left, not indicated (ask for the right spot).