Peirce Island is a little island right off this cute little touristic town of Portsmouth, with a lot of food and drink options after a nice cold dive. The dive site is at the beach right at the dog park in the island. With ample parking spot, very easy walk to the beach and with very friendly residents you can’t ask more from a dive site. However, as I heard, there is significant boat traffic in the summer time, so the site is mainly dove in the winter time.
However, the main reason we dive here is the sizes up to 3-5 inches, of nudibranchs I mean, observed here. One can speculate the reason for the ginormous sizes, like the sewage treatment plan, strong tidal currents carrying many nutrients. But, either case, abundant larger than average sized nudibranchs, mostly F. verilli, F verrucosa and D. frondasus, make this site a feast for the eyes and lenses. Trust me, if you have a camera, you will come up with awesome underwater photos you would proudly share or brag about.
Between the slack tides this site experiences very strong current, so we only get to dive at slack tide, both around low tide or high tide. However, there is a general expectation to experience lower viz around low tide, not sure if that’s accurate. Anyway, when you plan your dive as a rule of thumb that you should enter the water around low tide or approximately 1 hour and 15 mins after the high tide. Make sure you check the tide tables.
You can also check these web sites for the predictions of the currents at nearby points:
At this dive site there are two different kinds of terrain you get to enjoy. To reach both you go in the water and follow ~120 degree bearing. That is almost diving parallel to the beach, towards right. As you reach ~30 ft you reach the hydroid farm, the fun land for the big nudibranchs we see here. It gets hard to pass this site to see further down, because of the beauty of the hydroids and the nudis, especially if you are a photographer.
If you push yourself to explore further, you pass the hydroid farm to the steep wall covered in frilled anemones. This wall, covered with frilled anemones, go down to ~80 ft. I have not explored this wall as much, since I could not pass the hydroid farm for most of my dives. The divers who could mention that there is a car wreck and a pile of lobster traps at the bottom of the wall.
P.S. Thanks to Mike MacDonald for info on whats beyond the hydroid farm and Jerry Shine for slack tide timings.