At the end of September this year, we were diving off Catalina Island at Long Point. The viz was easily 100ft - absolutely gorgeous day. There were 8 of us on the dive.
About 1 minute into the dive I was looking out into the deep blue as we were descending and I saw a HUGE shape at the edge of vizibility. I didn't want to believe it but it was very clearly a big white shark, pointed directly at me. The girth of it was just crazy big - I swear it looked like the width of a car. I kinda freaked out and signaled everyone around me. It all happened very fast, but we didn't have any cover around us so we ended up just turning around and watching it come in to visit us as we sunk to the bottom (about 50ft). It came very slowly - very cautiously - within about 25 feet of us. We could see it crystal clear because the water so nice - could see its eyes moving around, its gills, etc... I know we were all a little panicky, but it became clear very quickly that we were in no danger. It was purely curious, and when it decided to leave it did one of those fish-jerk things and was gone at a crazy fast speed. It traveled about 70 feet in 3 seconds, from a complete stand still.
We all re-surfaced and sat on the boat re-hashing the experience. The boat captain said he'd been out there almost every day for 40 years and they'd only seen 1 other white shark. I've spoken with several other boats and most of them haven't ever had divers encounter one.
Needless to say, we all felt very fortunate to have the experience.
Also - last year at the end of March we were at the dive park in Catalina about a week after a big storm. A massive bait ball moved into the kelp forest for the entire time we were there. Being in the kelp with them, with 50+ feet of viz, and the sunlight coming down... It was probably THE most beautiful thing I've ever seen underwater.