Dam Sen Waterpark is in Dam Sen, about 20min cab ride from HCMC. Grab costs about 65 to 80K. The driver let us alight at the wrong park, and we had to walk a short distance straight down. There were three parks side by side.
Entrance fee was 150k VND per pax. Spent about 3 hours there at a leisurely pace. It was a small place. For some people, maybe 2 hours would be more than enough. We spent a lot of time just floating in the lazy river and jaccuzi.
There were no escalators so to get to the start of slides, one would have to climb stairs. There were also weight limits for some rides. One of the slides only allow 3 pax, so this might pose problems for couples. It looked fun. The pools at the end of each slide were about 1.1 to 1.3m, height limits for most rides were 1.4m. So for non swimmers, just need to relax at the end of the rides and stand up. The lifeguards were very alert, unlike most places.
There was a jacuzzi at 32 deg celcius, swimming pool, wave pool, several slides (with float or no need float), few eateries. Perhaps because of the weekday, only one eatery was opened. Prices start from 25K VND, not expensive at all. Lockers (one time use) costs 20K VND. Waterproof handphone neck pouch peddlers roam outside the park, selling each pouch at 30K each.