about 300' south (and a little bit east) of Split Rock is a great looking black boulder with probably 10 problems that mostly look in the V1-V3 range. The boulder is about 15' tall with lots of small edges.
We used to call it Serniuk Rocks. Kind of a Lame name. I did a lot of scrubbing there. I remember a cool problem that I used to do on the boulder to the west, on the westside. It has kind of a severe fall. You step across from a boulder on to the face. The crux is near the top. If you fall and hit the boulders below, you might die.
Lots of other boulders in the park besides the main Split Rock boulders and the large black boulder to the south. Just north of Split Rock, across the road, is a large boulder with a few hardish problems. Hiking west from Split Rock ~100 yards, there is a small boulder with a west-facing sds problem, in the V5 range. Another 100 yards west of this is a large boulder with 4-5 problems, mostly in the V0 range with at least one hard problem on the north face. There are a handful of other boulders visible from the beach on the southeast corner of the lake, with some unknown problems. Other large boulders exist off the trail that connects the main Split Rock and the beach, for those willing to explore.