Is it okay for me to go in Catalina's water if I will be on my period?

I am going on a trip to Catalina with my marine biology cl and we will be snorkeling. once in the morning and one in the evening. I asked my teacher and she said it would be fine if I want to wear a tampon or a pad because we're going to be in wetsuits but I'm scared of sharks! is it dangerous for me to be snorkeling?