Much of CR 104 runs through the David Allen Sarnoff Pine Barrens Preserve, a major New York State Conservation Area that was once owned by Radio Corporation of America.

[3] The route curves to the northwest and the speed limit increases once again to 50 miles per hour (80 km/h) before entering interchanges 64N-S of the Sunrise Highway (NY 27).

[4] After NY 27, CR 104 enters dense woods and the speed limit increases to 55 miles per hour (89 km/h).

[3] Soon after, CR 104 reaches its northern terminus, the Riverside roundabout just across the Peconic River from the community of Riverhead.

[2] The Riverside roundabout at the road's northern terminus was expanded to two lanes in October 2018 at a cost of $5.3 million, funded by Suffolk County.