Welcome to the scubaboard!
I think you should hire a guide or talk with some local divers/dive shops in person before going in the ocean. Monterey Bay will be much much different than a lake.
I'd recommend your first dive to be at Lover's Pt or Breakwater.
Lover's Pt. is relatively shallow, it takes quite a swim to get past 30ft. Lots of kelp though outside the winter time, so bring a cutting device and learn some techniques on how to dive and deal with kelp. In fact, bring a cutting device for all your ocean dives anywhere. The terrain in the shallow portion is nice and kinda "mountainous". There's lots of fish, algae, and inverts to see in the shallow side (10-25ft).
Lower's spans pretty wide out from the small beach, so on dives here you'll have to utilize a compass to make it back.
You are technically forbade by the city to dive there after 11am. Parking is free, either a 2 hour limit or residential from across the street.
Some quick kelp tips to remember are:
- if you get caught, relax and let the kelp loosen it's grip on you
- don't spin around in a circle unless you know how the kelp is caught on you
- to break kelp either bite it, cut it, or bend and fold it.
- you can swim up through kelp to reach the surface if you do it slowly.
Breakwater is the popular go-to spot for most Basic OW classes in our area. You usually dive to depths between 40-60ft depending what part of the site you dive.
It's relatively easy to do a dive with little thought to navigation, as you can follow the breakwater wall through your whole dive. Keeping it on your right means you're heading away from shore, on your left it means your going into shore.
When you're ready for some more compass work you can dive to the Metridium fields or along the Pipe. There's always plenty of new things to see here; tons of life on and off the wall.
Parking here is metered, $1.50/hr or $10 for the whole day.