It's actually quite easy to hit the sand channel. As you swim out of the cove, you will begin to to see the surface kelp walling you off from further surface swimming. Shortly beyond this border, a clear channel, extending out to sea, is seen in the kelp. This is the Sand Channel. Short hops underwater beneath the kelp will get you into this channel.
Now that you're in the channel, a popular landmark as you swim out on the surface is the "Shar Pei Rock". This rocky wash rock sits underneath the bluff. It looks remarkably like the head of a Shar Pei dog that is looking out to sea! Placing this distinctive rock on your left, as you look float in the sand channel and look out to sea, will place you over 35' of water.
This is a popular place for most divers (especially those with scooters) to drop.
However, this is a bit more than 400' of underwater swimming to get to Hole In The Wall (HITW). If HITW is your goal, and you want to conserve bottom gas, then just keep swimming out the channel on the surface, and drop when it feels good. As a navigation reference, when you're parallel to the Shar Pei rock: when you look back at the ramp, the ramp will be a bit more than 400' away. So, HITW is about as far away as the ramp, when viewed from Shar Pei rock.
Have fun!
All the best, James