At the eastern end of Ryer Island, the road crosses Steamboat Slough on the Howard Landing Ferry, a cable ferry.

[3] The route includes the toll-free Howard Landing Ferry, where the cable-drawn vessel J-Mack takes vehicles across Steamboat Slough.

[4] Both the Howard Landing Ferry and the Ryer Island Ferry along State Route 84 are the only state-run ferries, and there are no plans to replace them with bridges due to the low traffic numbers around Ryer Island,[5][6] The only road bridge connecting Ryer Island is on its north side, which results in longer commutes for residents if one or both ferries shutdown.

[7] Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage.

[8] Segments that remain unconstructed or have been relinquished to local control may be omitted.