Mud Spring, locally known as Sulfur Spring, is a 4th magnitude spring with an oval-shaped pool about 85 feet long and 65 feet wide. The spring flows from a vertical vent in the center of the pool, producing a prominent boil on the surface. The spring forms the head of Mud Creek, with the discharge flowing down a meandering run toward the southwest for about 1 mile to Little Lake George. The spring is situated along a hiking trail and is a popular picnic area in the state forest.
Mud Spring is located on state land about 1.5 miles south of Welaka. From the intersection of State Roads 309 and 308B in Welaka, drive south on State Road 309 for 1.5 miles and turn west onto State Forest Trail and continue past the gate for 1.1 miles. The spring is approximately 0.2 mile west of the trail.