To reach Third Machias Lake, take the Little River Road (which runs north off the Stud Mill Road along the east side of the Machias River). Turn left after 4 miles onto a side road that leads to the boat launch. This is a logging road, beware of log trucks. Pull OVER when you see one and let them pass. They are going really fast with really big loads of logs.
We park at the boat launch. There has usually been 2-3 campers there when we park there. There are porta potties there. But…. we don't stay there. Kayaks in, camping gear into the boats. Off we go. It can be a rough paddle if it's windy. This lake is HUGE and can and has gotten 2-3 foot waves when the weather is not so great. It usually takes us about an our to get to the island we camp on. It has no name I know if but, many people call the next island past ours, Fairy Island.
I actually prefer Fairy Island. it's more open, smaller island, and better trees for hammocks. Plus the breeze there is awesome but bring a big tarp and road to give yourself a wind block.
The kayaking in this area is the BEST I have had in Maine. It's an absolute wonderland of variety. We took many river routes going out of the lake, into other lakes, through marsh/swamp, portaging beaver dams and such. One time had to go over a dirt road. Hardly ever ran across a person except this one time, a guy who has a cabin on the main shore not too far from our island (maybe 20 min paddle) was out fishing and invited us to his cabin where he and his wife gave us drinks and made awesome food at their campfire. They were so cool. I hope I have a house like that at some point.
Anyway; if you crave adventure this area is for you. Just jump in your boat, with your gear, and hunt down an island of your choosing. There are a bunch out there. Beware of rocks even in deep water! The glacier rocks are absolute huge. See my photos for yourself. Respect nature. Don't leave your garbage out here, no one wants to see that!