from New York, travel the Garden State Parkway, use Exit 63. On US 9, look for the Manahawkin exit. NJ Route 72 East will take you right to LBI.

from Philadelphia, Pennsylvania Cross the Benjamin Franklin Bridge into New Jersey and follow the signs to Cherry Hill (Route 38 and 70) and the beaches (mainly you'll be staying on the left).
Once you've made the left onto the ramp that enters Route 38, you'll have to quickly get all the way to the right onto Route 70.
Take 70 until you reach the junction for Route 72 East (It's a circle, but you don't have to go around, stay to the right).
Follow 72 for 26 miles right onto the island.
The trip takes about 1 and 1/2 hours.