The bridge that holds the entire length of Route 12 begins just south of Lavender Town. Shortly after its starting point, the bridge comes to a three-way intersection, with the left fork leading to a dead end. The right fork turns south east of the intersection and comes to another intersection, leading to another dead end path holding a sign informing Trainers of Lavender Town to the north.
South of this intersection is a gate separating the north portion of Route 12 from the Silence Bridge.
The Silence Bridge makes up most of Route 12. The first intersection on the Silence Bridge portion of Route 12 is yet another of the three-way variety. The left path leads to a dead end while the right path continues southward. After a brief southward stretch, the bridge turns southwest to avoid an island in the water, eventually intersecting a north-south bridge segment on the western edge of Route 12. The main path of the route uses a portion of this segment before turning east onto an east-west segment. Route 12 then makes a sharp south turn onto another continuous bridge piece. Route 12 gradually makes its way south, passing a fishing pier before arriving at an island, the first piece of solid land along the route's main path since Lavender.
On the west shore of the island, the Silence Bridge resumes, making an upside-down "U" as it proceeds south. After a short time, the bridge makes a turn to the east. This segment of the bridge comes to an end roughly 15 paces east of this point, but Route 12 has already turned off onto another bridge segment, a north-south stretch, by this point. About eight paces south of the intersection between the two segments is the designated "Sport Fishing Area" at the intersection of Routes 11 and 12.
Continuing south, the bridge turns to the southeast just ahead of another island. The home of the younger of the Fishing Brothers is located on this island. West of his house, the bridge resumes, traveling to the south and east before coming to an end just after an intersection with another segment. This segment carries the route south to a series of intersections. The two westward routes in this area lead to a peninsula containing a forested area accessible only by using Cut. The lone eastward path leads to another fishing pier. Just south of the southern peninsula path, the route briefly turns to the east before returning south.
At the next intersection, the main path of the route continues south while a westward path leads to the only grassy patch on Route 12. Cut is required for access, however.
The main path of Route 12 continues south along a tree-lined shoreline before becoming Route 13 two paces south of the grassy patch.
Fishing Guru's/Mr. Dazzling's house
This section is incomplete. Please feel free to edit this section to add missing information and complete it. Reason: Initial size record to beat.
A sleeping Snorlax is often found blocking the intersection between Routes 11 and 12. To move it, a Poké Flute is required. Also, in Generation III, TM16 (Pay Day) was replaced with TM48 (Skill Swap), and after the Fishing Guru's younger brother gives the player a Super Rod, he will give away a Net Ball if he is shown a Magikarp of a certain size.
Generations II and IV
Some changes were made to this route in Generation II, most of which were carried through to Generation IV. In particular, the route was shortened considerably and the grassy areas along the route were removed. The gate between Silence Bridge and Lavender Town was also removed and the number of Trainers on the route was reduced to three (although this remains eight in Pokémon HeartGold and SoulSilver).
In Generation II, the signpost at the north end of Route 12 now reads "Fishing spot". To compensate, the Route 12 notice present on this sign before was moved to the former "Sport fishing area" sign at Route 11. The signpost on Route 13 just southwest of Route 12's end, however, still reads "Route 13: North to Silence Bridge".
The Battle Dome, possibly located on this route. Note the body of water lying behind the facility, possibly the ocean to the east of the route.
In the main series
Route 12 may have been featured briefly at the start of Tactics Theatrics, since the Battle Dome is stated to lie just to the south of Lavender Town, and the Dome appears to be situated at the edge of a large body of water.
Route 12 debuted in Wake Up—You're Snorlax!, where a bike race was taking place through the route, but a Snorlax was blocking the road. A Swimmer and a Bug Catcher had already tried to make it move, but failed. Red eventually figured out a solution by using the honey that had fallen from a Beedrill hive onto Saur's head as a bait to get Snorlax to wake up and move. The plan worked, but it also caused Snorlax to follow Red all the way to the finish line, where he eventually caught it.