Numerous springs feed Merritts Mill Pond. Jackson Blue Spring is the main spring at the head of the pond. It is situated about 10 ft (3 m) west of the diving platform. Spring pool diameter is approximately 240 ft (73.2 m) southwest to northeast and 233 ft (71 m) northwest to southeast. Maximum depth over the vent is 16.5 ft (5 m). The vent is elliptical and approximately 5 ft (1.5 m) high and 25 feet (7.6 m) wide. Limestone is exposed near the vent, and it bears backhoe scars. Clear bluish water issues from the vent. A boil is slightly visible at the surface. There is approximately 40% algae coverage on the pool bottom and very little aquatic or emergent vegetation. The spring pool is a designated swimming area separated from the rest of Merritts Mill Pond by a chain link fence across the channel approximately 300 ft (91.4 m) downstream. The southern shore of the spring pool meets a lowland cypress-gum forest. The northern half of the pool is bordered by high ground sloping upward to nearly 20 ft (6.1 m) above water level. Most of the high ground is cleared and grassy. All nearby uplands are developed. There are buildings and a parking area constructed on the uplands. Surrounding the spring, are a concrete retaining wall near shore, slides, a diving board, and picnic tables. An extensive underwater cave system has been mapped at Jackson Blue Spring.
Jackson Blue Spring is about 5 miles (8 km) east of Marianna at the northeast end of Merritts Mill Pond. From the intersection of US 90 and SR 73 in Marianna, head east 1.4 miles (2.3 km) on U.S. 90. Turn north (left) on SR 71 and travel 1.2 miles (1.9 km) to the intersection of SR 164. Turn east (right) and drive 3.3 miles (5.3 km) to the county park entrance on the south (right) side of the road. The spring is 0.1 mile (0.2 km) southeast of SR164 in a county park.