A cheap, practical option is to create a dry viewing window below the surface rather than submerge the camera directly. Two low-cost ideas from the community are:

• Use a small aquarium/tank, partially submerged, so it creates a dry space you can shoot into through clear glass.
• Build a simple viewing box with a flat plate-glass bottom, sealed with silicone. Adding a dark cloth around the opening helps cut surface glare.

A flat glass panel is better than a scratched bowl because it’s clearer, easier to aim, and avoids the distortion of curved glass.

If you do want the camera itself below the surface, a flexible underwater bag can be a budget alternative to a full rigid underwater housing. The tradeoff is limited access to controls, so it works best if you preset exposure mode and focal length before shooting.

In short: for the least money, use a flat-glass aquarium or DIY viewing box; if you need true underwater placement, look at a basic soft underwater bag.