The highway returns into Rochester and enters Lakeville between Little Quittacas and Great Quittacas Ponds. Route 18 joins Route 105 for a  concurrency, running along the western shore of Assawompset Pond.
The highway reenters Rochester and passes through Lakeville between Little Quittacas and Great Quittacas Ponds. Route 18 merges with Route 105 for a shared stretch, running along the western edge of Assawompset Pond.