Mosquito Springs Run is a 3rd magnitude spring with a series of vents in the main pool and run (labeled 1, 2, 3, 4, and 5). The spring head is at the bottom of a steep ravine and has two main vents (1 and 2) in a pool about 20 feet long by 10 feet wide. Vent 1 is in the south part of the pool and vent 2 is in the north part. Green algae and white sulfur-reducing bacteria are present in the pool. About 140 feet down the run, a tree across the run can be used as a bridge to walk to the other side of the run to sand boil 3, situated in a small run on the right (south) side of the main spring run. Sand boil 4 is in the main spring run about 20 feet toward the northeast of sand boil 3. The ravine becomes less steep downstream and the run flows into a broad wetlands area. Sand boil 5 is in a seepage area to the south-southeast of vent 3 (a camping area is on the upland area to the east of vent 5).
Mosquito Springs Run is located in the eastern part of the Alexander Springs Wilderness Area in the Ocala National Forest. From the intersection of State Road (SR) 44 and County Road (CR) 42 just west of the St. Johns River, drive west on CR 42 for 1.7 miles to Forest Road 541. Follow the main jeep trail for 2.4 miles until it ends at a 'T' in the trail. Turn west (left) at the 'T' and drive 0.25 mile. Park on the right at the trail head. Walk in a northwest direction on the trail for about 1300 feet to the head of a shallow ravine. Just before the ravine, walk on a minor trail toward the right (north) for another 600 feet. Then veer to the left down the ravine to the spring head of Mosquito Springs Run.
Motorized vehicles are prohibited in the wilderness area. Access information can be obtained at the Seminole Ranger District office of the Ocala National Forest on SR 19 in Umatilla.