Many come to mind. I prefer hiking along water or to a body of water if its raining. Everything in the woods is wet and I like the interesting photo ops it brings. Here is a brief list.
1. A pleasant walk to Zealand Hut via Zealand Trail is a nice option...not steep, easy footing and lots of the crossings have bridges. Its really beautiful in the Zealand "rain forest". Many photo ops
2. Ripley Falls, Nancy Cascades...really any waterfall, as long as its not raining too hard. I've been told that Ripley Falls are great to photograph on a not-so sunny day. Both sets of falls are beautiful in any weather.
3. Three Ponds Trail to Donkey Hill Cutoff to Mt Kineo Trail loop back to the car. Many varied things to look at, from wildflowers, to ponds, to beaver ponds, and different forests.
4. Hancock Notch Trail-If you're feeling adventurous and want to cross some streams, get a couple cars and park one at Hancock Notch Trailhead and one down at Sawyer River Trail along the Kanc and do the 10 mile loop. Its kind of tough to follow at the height of land of Hancock Notch, but once you get past that it is one of the most unique trails I have ever traveled.
5. Any trail with a profusion of moss.....the scent of a forest is different when its all wet, esp in mossy areas.
I could say every trail, but these come to mind. Now I want to hike on a rainy day!
grouseking