Here is the full list of all 20 Sex on Beach achievements.
1 level complete
2 level complete
3 level complete
4 level complete
5 level complete
6 level complete
7 level complete
8 level complete
9 level complete
10 level complete
11 level complete
12 level complete
13 level complete
14 level complete
15 level complete
16 level complete
17 level complete
18 level complete
19 level complete
20 level complete