Dam Sen Water Park is a very local answer to Ho Chi Minh City's heat: slides, pools, wave areas, and plenty of families escaping the concrete glare. It sits beside the wider Dam Sen cultural park in District 11, well away from the usual District 1 sightseeing loop.
Do not expect a polished resort atmosphere; expect noise, colour, wet concrete, and a crowd that is mostly there to have fun rather than pose for visitors. It is best with children or a group, and it makes most sense on a hot day when another museum would feel like punishment.