Snorkelers! Help me!

This is probably not the place to post this but I need help from some fellow beach lovers and snorkelers. I live in California and people are always going snorkeling but I'm not sure how they do it. People just act as if the ocean is calm enough to go and snorkel in. I see people coming in with gear and they dive straight into the water and then come back out hours later. Aren't they afraid of the tide and not being able to swim back???? You can only snorkel in calm waters so I'm so confused. I know there are certain calm spots but HOW DO YOU GET THERE? Please someone help me understand because I love to swim in the ocean and I want to go out deeper