Montage resort was long ago known as "Treasure Island,” and the park there is still called that. It is a shallow dive and you can see a reef running parallel to shore. There's an opening with access to the back side of the reef. And at the North end of the beach is a large rock outcropping the has many nooks and crannies to explore.
Take the short driveway off PCH (opposite Wesley Dr.) and park in the covered parking. They have machines that take credit cards. Walk down a paved path through these elegant hotel grounds to the sandy beach and remember, it is a resort so please keep noise to a minimum!
There are facilities with both restrooms and showers located at the cove. You can always stay at the Montage Resort the night before for a relaxed morning and easy commute to the dive site.