Swimming/Canoeing
The water in South Branch Pond is so clear that some days you can see right to the bottom, so this is a prime place for swimming on a hot day. If you like canoeing or kayaking, the pond is large enough for both and for a small fee visitors can rent a canoe from the park (I believe it is only $2.00 an hour). The ranger station even has it's own supply of life jackets for those visitors wanting to get out on the water. If you take your canoe across to the side of the pond opposite the docks, you will find a small stream connecting the upper pond and the lower. When I was in high school, my best friend and I came up this way in a canoe and jumped from the cliffs at this pond. I'm going to say "Don't try this at home" because I don't want some slap-happy tourist taking the jump and then suing me for damages. So - partake in this activity AT YOUR OWN RISK. There - glad that's out of the way :)
Hiking
There are many different hiking trails around South Branch Pond, and no matter what level of difficulty, how long you want the hike to be, etc - you will always find something for you. Here are several of the hiking trails that you can find around the pond. Some I have been on and some I have not, but all of them are worth a look. :)
This trail winds around the left side of the pond. Follow the road until you reach the Pogy Notch Trail. This trail ultimately leads to Russell Pond, but you will see several other hikes listed on the same sign - one of these is Howe Brook. The hike is only about four miles round trip, and the terrain makes for an easy, leisurely hike. Once you reach brook, the trail follows it upstream and passes a series of pools and waterfalls. This is a great hike to start on in the morning during the summer, as the pools and waterfalls make for a nice place to stop and eat lunch before turning around and heading back to the campground for a dip in the pond. :) If you're daring enough to brave the ice cold water flowing straight off the mountain, some of the pools at Howe Brook are big enough to swim in - but take it from my first-hand experience....even in a heatwave in August, they are ice cold!
South Branch Falls
This waterfall is not very big, but it's a great place to check out because there are usually not many people there. If you want a little more out of the way place to have a moment of peace and quiet with nature, try taking a side trip down this trail. Once you park at the campground, you will need to hike back up the road you came down a piece to get to the trail-head. The hike is only about 2 miles round trip, and it's a very easy hike for people of all ages. Although the waterfall is small enough that it seems very inviting to take a dip and play - keep in mind that there are a LOT of spiders making their home in the rocks. While Maine does not have poisonous spiders - not many would want to go swimming even with harmless ones. ;)
North Traveller Mountain
To get to the trail head for North Traveller, take the Pogy Notch Trail. A short distance down the trail, you will find the sign for North Traveller directing you to the left and up the mountain. This hike will take the better part of the day. Even though the trail is only 2 miles to the mountain top, the mountain itself is over 2500 feet. This steep incline makes the hike more challenging than it's short distance implies. Most of the trail is exposed, but as a result this makes for many impressive views with the most breath-taking being the view from the summit. Once you reach the peak of North Traveller, you have a clear view across the valley of Knife's Edge on Katahdin. Bring plenty of water when making this climb, and be sure to check out the spring part way up the mountain (clearly marked by the park with signs). When I first hiked this mountain, I was just in grade school and was maybe 10 years old. So if you have a fit grade-schooler and the conditions are good, you should be able to make this hike. Any younger children would probably have difficulty with this one, though. The last time I made this hike, I was 17 years old, and it's been far too long since I've been back! Believe it or not, you are going to have to wait for photos from me because I can't find ANY photos to put on here that I like! haha
There are many more hiking trails to check out around South Branch, and as I explore them - I will definitely pass them along. But for now, this is all you get ;)