Thanks for the link and water conditions. Vis sounds great. Typical vis around here is only a few inches to a few feet in most places, but the water is balmy around 70 for the summer
Cathedral Rock sounds like an interesting site. How difficult is that entry?
I'd say the entry is moderately difficult, especially at mid-tide or lower when one is required to step around the more slippery, more rounded rocks that have been exposed. More a hassle than a danger, but, nonetheless, I only dive it solo when the sea state and tide makes the entry more benign. I always remind myself how easy it is to fall, knock oneself out and drown in 6 inches of water.....
So, I usually check NOAA's marine forecast and avoid Cathedral if the wind is from the east or if residual east swells are likely:
http://weather.noaa.gov/cgi-bin/fmtbltn.pl?file=forecasts/marine/coastal/an/anz250.txt
Tide chart for Rockport:
Tide/Current Predictor
I also check the weather and avoid Cathedral if the rocks are wet from rain:
10 Day Weather Forecast for Rockport, MA - weather.com
Most of the work of diving Cathedral Rock is the hauling of gear down from the road to the entry's staging area. Parking is free, by the way. Divers usually make at least two trips, sometimes three, because of the treacherous nature of the route over the jumble of granite slabs. Each trip is a minimum walk of 40' from one's car to the edge of the slope, then another 75' weaving across and between the granite rocks, some of which drop 4' to the next slab or point. See the first pic below.
The entry is usually from the long flat rock seen in the second picture. It's about 5' above the surrounding rocks, so a giant stride can be done at high tide. At lower tides, entry is made by stepping down into a notch in the crease (left of center in the picture), then taking one more large step to the main rock below. Then one sidles along the wall created by the long flat rock, holding on because the bottom is usually slippery from algae. I like to put on my mask at that point, then grab my fins off the rock and carry them as I continue to walk carefully a few more feet until the water is deep enough to swim. I put my fins on when deep enough.
To exit, I just plant a foot into the notch of the same crease and pull myself halfway up, then a couple more steps to get out. I usually do it with gear on except for fins, mask, catch bag and spear. If you're lucky enough to exit at high tide, you might be able to beach yourself on top of the long flat rock!
All in all, most people find Cathedral well worth the trouble, since it has the fastest slope to deep water of any of the shore dives on Cape Ann and it has some impressive rock formations and often more varied marine life.
Dave C
View of the staging area and entry from the top of the slope.
View of the entry from the staging area.
Getting out on these rocks that are slippery is not the easiest task. 
But the walk to the shore line is very, VERY long... If you search the forum, you will find plenty information, including some very recent reports, and everyone emphasize the walk needed... I went there several time for family or hike, love the place, but diving will be another story... Not sure where the entry would be either as this is all rocks.
