You can either follow directions to the Flats from nearby cities or use the Google tool. 

From Harrisburg area (50 minutes to 1 hour from Harrisburg):

-Take 283 south to the Swatara exit (441)

-At the top of the ramp, turn left onto 441 south

-Follow 441 south to Columbia

-In Columbia, turn right on Locust St. to stay on 441 south

-At the bottom of the (short) hill, turn left on Front St. to stay on 441 south

-Continue south for 3 miles on 441, then continue straight once 441 ends (at jct. w/ 999) - this is called Water St.

-Follow Water St. around 90 degree turn to the left, then turn right on River Rd.

-In <1 mile, turn right onto Blue Rock Rd.  The boat launch is across the tracks, and the parking lot is to the left immediately before the tracks.

From Lancaster area:

-Take Rt. 30 west (toward York)

-Exit for Columbia and take 441 south

-In Columbia, turn right on Locust St. to stay on 441 south

-At the bottom of the (short) hill, turn left on Front St. to stay on 441 south

-Continue south for 3 miles on 441, then continue straight once 441 ends (at jct. w/ 999) - this is called Water St.

-Follow Water St. around 90 degree turn to the left, then turn right on River Rd.

-In <1 mile, turn right onto Blue Rock Rd.  The boat launch is across the tracks, and the parking lot is to the left immediately before the tracks.

From York area: 

-Take Rt. 30 east (toward Lancaster)

-Exit for Columbia and take 441 south

-In Columbia, turn right on Locust St. to stay on 441 south

-At the bottom of the (short) hill, turn left on Front St. to stay on 441 south

-Continue south for 3 miles on 441, then continue straight once 441 ends (at jct. w/ 999) - this is called Water St.

-Follow Water St. around 90 degree turn to the left, then turn right on River Rd.

-In <1 mile, turn right onto Blue Rock Rd.  The boat launch is across the tracks, and the parking lot is to the left immediately before the tracks.

Google directions

-follow the link and input your address of origin for customized directions