Is it safe to snorkel if you can't swim?
Considering this, can you drown while snorkeling?
Yes, you can. It's not common that it would happen but being in the water always entails the risk of drowning. Most accidents do happen when the snorkeler gets exhausted from either being in the water too long or fighting currents.
Also Know, is it hard to learn to snorkel?
Even if you're not, it's not hard. Snorkeling in the ocean is much easier than in fresh water (like a cenote) because the salt water makes you more bouyant. I recommend using a life jacket for your first time to allow yourself to become familiar with the feel of the snorkel and mask.
Your best bet is to get 12-15 inch tube and hold your breath as you sink in, but ideally, if you want to explore the waters underneath, try getting a scuba certification. An average depth of around less than 1 meter is considered to be the norm for snorkelers.