Snorkeling

I don't have any experience with underwater photography.  I will be snorkeling in Mexico in the Playa del Carmen/Cozumel region.

I want to bring the best equipment I can in order to obtain the best possible pictures.

I am wondering if I should use one of the clear waterproof vinyl pouches with my OM-D and if so what focal length/speed lens would be best? (Note that a dedicated underwater hard camera case is probably out of my price range)

Working with a camera in a pouch might be awkward and difficult to shoot with.  Alternatively might I likely get better overall results with a dedicated underwater point & shoot (with built in flash) and no pouch?  If you have experience with underwater point and shoot, what point & shoot would you recommend?

Any tips that might obtain the best results would be appreciated.