A mask and snorkel will not be hard to find in SP, buying or renting. Owning a good mask and snorkel is by far better. To know if it fits your face correctly, simply place the strap out of the way, hold the mask up to your face and inhale through your nose so as to suction cup it to your face, not to hard now, and face the ground, if it stays on and holds a seal with your hair outta the way ofcourse, than it fits you.