Seoul's Strangest Subway Stations: Loops, Twists & Records

Most Seoul subway stations do their job and nothing else: a concourse, a platform, a train every few minutes. A few don’t. There’s a tunnel on Line 4 that twists over itself so trains can switch sides of the track, a loop on Line 6 that brings you back where you started, a Line 2 branch that runs four-car trains, and a farm growing salad greens one floor under a Line 7 street.

This is the third piece in our Seoul subway series. For the deepest stations and the Sinseol-dong ghost platform, see Seoul’s most beautiful subway stations. This one is about odd engineering, odd operations and odd records.

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Why do Line 4 lights flicker near Namtaeryeong?

Because Line 4 changes owner, power system and direction between two stations. North of Namtaeryeong, Line 4 was built as part of the Seoul subway. South of Seonbawi, trains run on the Gwacheon and Ansan lines, built by the national railway. The two systems were designed differently, and the joint between them is one of the oddest pieces of track in Seoul.

Namtaeryeong and Seonbawi (Line 4)

When the Gwacheon Line (Sadang–Geumjeong) was built to join right-hand Line 4 to the left-hand Ansan Line, the two directions met head-on. A 2004 explainer on the Seoul city government’s news site describes the fix: a kkwabaegi tunnel between Namtaeryeong and Seonbawi, where one single-track bore crosses over the other. Ride south from Sadang and the train runs on the right; by Seonbawi it is running on the left.

The same stretch is a neutral section. A 2024 article on the city’s news site lists Seonbawi–Namtaeryeong alongside Seoul Station–Namyeong and Cheongnyangni–Hoegi on Line 1 as the places where the lights dim or the air conditioning pauses for a moment. Nothing is wrong. The train is cutting outside power while it switches between DC and AC.

Get off and look: ride from Namtaeryeong to Seonbawi, watch the cabin lights during the run, then notice that trains at Seonbawi now pass each other on the left.

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Which Seoul subway lines loop, split or shrink?

Line 6 has a loop, Line 5 has a fork, and Line 2 has two branches with short trains. None of these are hidden. You just need to read the destination board before you board.

Eungam (Line 6)

Line 6 doesn’t end in a straight line. When the line opened in December 2000, Seoul Shinmun reported that it included a circular section that leaves Eungam, runs through Yeokchon, Bulgwang, Dokbawi, Yeonsinnae and Gusan, and comes back to Eungam. Bulgwang and Yeonsinnae are transfers to Line 3.

The practical effect: from Yeokchon you can’t simply ride “back” one stop to Eungam. You go around the loop.

Get off and look: board a loop train at Eungam and stay on; it brings you back to Eungam after Gusan.

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Gangdong (Line 5)

East of Gangdong, Line 5 forks. One branch runs via Dunchon-dong to Macheon. The other runs via Gil-dong to Sangil-dong and on to Hanam, after the Hanam extension opened to Hanam Pungsan on August 8, 2020 and to Hanam Geomdansan on March 27, 2021. Trains for each branch alternate, so service further east is less frequent. A 2017 Seoul city transport explainer noted weekday midday gaps of up to 12 minutes.

If you’re on a Macheon-bound train and need Hanam, get off at Gangdong and cross to the opposite platform.

Get off and look: check the departure board at Gangdong; it is one of the few places in Seoul where the next train’s branch matters more than its direction.

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Sindap (Line 2, Seongsu branch)

Line 2 is a circle, but it has two branch lines that share its color. The Seongsu branch runs Seongsu–Yongdap–Sindap–Yongdu–Sinseol-dong with 4-car trains, against 10 cars on the circle. Both branches double as access tracks to depots (Gunja on the Seongsu branch), so at rush hour you may see empty trains heading in or out.

Sindap is the place to see it: an above-ground stop where you can watch the short trains pull in. It also has a small garden on the platform, which we cover in Seoul’s quietest subway stations.

Get off and look: count the cars as the train pulls into Sindap, then ride one stop to Yongdap, where the line runs past the Gunja depot.

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Kkachisan (Line 2 Sinjeong branch, Line 5)

The other branch, from Sindorim via Dorimcheon, Yangcheon-gu Office and Sinjeongnegeori, ends here with 6-car trains, and also serves the Sinjeong depot. Kkachisan is an odd transfer. The Line 5 platform is five floors down (B5). Even so, in 2015 data cited by Seoul Shinmun, the Line 5 → Line 2 transfer took an adult only about 15 seconds, among the shortest in the network.

Its depth made it one of the hardest stations to fit with a street-to-platform elevator. The lift finished in December 2025 needed what the city calls Korea’s first “ㄷ-shaped” excavation and a curved shaft.

Get off and look: time your own Line 5 to Line 2 transfer, then ride the new elevator from B5 to the street.

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Which Seoul station has the longest transfer?

Hongik Univ., between Line 2 and AREX, in the most-quoted figures. In December 2015, Seoul Shinmun published transfer times for about 100 stations, from city data released through a Seoul Metropolitan Council member. These figures are a decade old and some corridors have changed since.

Hongik Univ. (Line 2, AREX)

Seoul’s own transport explainers list Hongik Univ. (Line 2–AREX) with Jongno 3-ga, Jamsil, Express Bus Terminal, Nowon and Seoul Station among the long transfers worth avoiding if you have a choice.

Get off and look: follow the AREX signs from the Line 2 gates and time the walk yourself. Allow at least five minutes with a suitcase if you’re catching an airport train.

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Jongno 3-ga (Lines 1, 3, 5)

Third-longest transfer in 2015, Jongno 3-ga also held two other records in a 2004 piece on the city’s news site: the most exits in the network (15) and the longest moving walkway (100 m, on Line 3). Expect the exit count to differ slightly today.

Get off and look: walk the moving walkway, then come up at whichever exit is closest to Ikseon-dong or Jongmyo. Our Jongno 3-ga food guide covers what’s above.

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Nowon (Lines 4, 7)

Nowon is the most awkward transfer by design. A 2023 explainer on Seoul’s city news site gives three reasons. Line 4 is elevated while Line 7 is underground. The Line 4 station sits east of the junction because tracks to Changdong Depot needed a gentle slope. And the bridge-type corridor between them has no moving walkway. It ranked last nationwide in the Korea Transportation Safety Authority’s 2014 evaluation of urban rail transfer stations.

Get off and look: the climb from Line 7 up to the open-air Line 4 platform. For food nearby, see our Nowon guide.

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Which Seoul subway station has the most lines?

Gimpo Airport, with five. Wangsimni is the busiest four-line hub on the east side.

Gimpo Airport (Line 5, Line 9, AREX, Gimpo Goldline, Seohae Line)

The Seohae Line’s Daegok–Sosa section opened on July 1, 2023. According to the Seoul city government’s news site, that made Gimpo Airport Korea’s first five-line transfer station, joining Line 5, Line 9, AREX and the Gimpo Goldline. Not every transfer is equal: the city lists Line 9 ↔ AREX here as one of Seoul’s easiest transfers, while the new Seohae platforms sit at the bottom of long escalators, and the city suggests older passengers take the lift.

Get off and look: count the five line colors on the transfer signs, and take the Line 9 express if you’re heading for Gangnam.

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Wangsimni (Line 2, Line 5, Gyeongui-Jungang, Suin-Bundang)

The city’s news site calls Wangsimni the “transfer mecca” of eastern Seoul, with Lines 2 and 5, the Gyeongui-Jungang Line and the Suin-Bundang Line. The Gyeongui-Jungang ↔ Bundang transfer is on the city’s list of easy ones. Since December 24, 2024 there has been an unexpected extra: Seongdong-gu turned about 200 m² of empty concourse into an indoor garden, Wangsimni Araesupgil (“forest path below”).

Get off and look: the indoor garden on Line 5’s B1, between Exits 4 and 5. Then eat in the alleys above with our Wangsimni & Haengdang guide.

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Where is the widest platform gap on the Seoul subway?

At curved platforms, and in 2022 data the widest was at Sungshin Women’s Univ. on Line 4. The city explains the cause: a straight 20 m car on a curved platform leaves about 9 cm at its ends, but up to 21.5 cm in the middle, depending on the curve. Of 19,256 boarding positions at Lines 1–8 stations, 3,395 have a gap over 10 cm.

Sungshin Women’s Univ. (Line 4)

Newsis reported in November 2022, from Seoul Metro data submitted to the National Assembly, that boarding position 3-3 at Sungshin Women’s Univ. had a 28 cm gap, the widest in Lines 1–8. Chungmuro (Line 3) followed at 26 cm, Dongguk Univ. at 23 cm, and Sindorim (Line 2) and Hoehyeon (Line 4) at 22 cm. In April 2023, Sungshin became one of five pilot stations for folding automatic footboards that rise before the doors open and drop once they close, alongside City Hall, Chungmuro, Dongguk Univ. and Dongdaemun History & Culture Park.

Get off and look: the footboards in action and the “mind the gap” stickers. Watch your step with a suitcase.

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What's hidden in Seoul's unused station space?

Farms, film sets and, briefly, a horror-game set. Seoul Metro rents out idle space, and in 2022 the subway hosted 216 film shoots.

Sangdo (Line 7)

Metro Farm opened on Sangdo Station’s B1 on September 27, 2019, built by the city, Seoul Metro and the agri-tech company Farm8. Seoul’s news site called it Korea’s first smart farm in a subway station. At opening it had LED-lit growing rooms producing greens around the clock, a robot-run container farm and a farm café. After a renovation in early 2022, Seoul Metro described it as the largest of its Metro Farms; others operate at Dapsimni, Chungjeongno, Euljiro 3-ga and Cheonwang.

Get off and look: salads and farm greens from the kiosk or the salad vending machine; the growing rooms themselves open only for booked Farm8 Academy sessions (minimum 20 people). An August 2026 visit listed hours of 09:00–18:00 Tuesday–Friday and Sunday (break 13:00–14:00), 10:00–19:00 on Saturday, closed Monday. It is in the passage by Exits 1 and 2.

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Yeongdeungpo Market (Line 5)

Behind a yellow steel door at Yeongdeungpo Market are two floors, B2 and B4, of bare concrete. The city’s news site says they were built to connect with a planned Line 10 that was later cancelled. From May 19 to June 11, 2023 the space became “Hellstation”, a Diablo IV walk-through run by Blizzard, Cheil Worldwide and Seoul Metro. The same article names this space, Sinseol-dong’s unused areas and Sindap’s garden platform as the subway’s best-known filming locations.

Get off and look: the hidden levels are closed outside events, but the station was redone in 2020 as an art station on the theme “rediscovering the market”, with stair art and the Big Mirror platform gallery on B5.

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Where does the Seoul subway come up for air?

More often than you’d think. A 2015 city planning release counted 81.9 km of surface or elevated rail inside Seoul, national railway lines included, and among the subway lines it listed 18.9 km of Line 2, Line 3 between Geumho and Apgujeong, Line 4 at Changdong–Danggogae and Dongjak–Ichon, and Line 7 between Cheongdam and Konkuk Univ.

Dongjak (Lines 4, 9)

Dongjak Bridge, finished in 1984 as the 14th bridge over the Han, carries Line 4 down its middle, flanked by a six-lane road. The city says it was Korea’s first bridge built for both cars and subway trains. Dongjak Station is where Line 4’s above-ground stretch to Ichon begins, so Line 4 stops here in daylight. Line 9 also stops at Dongjak.

Get off and look: wait for a Line 4 train on the open-air platform, then sit on the river side for the crossing toward Ichon.

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All 14 stations at a glance

🚇 Seoul's strangest stations, by what makes them odd (sources at the bottom)

Station	Line(s)	What’s odd	What you can see
Namtaeryeong / Seonbawi	4	Twisted tunnel flips right-hand to left-hand running; DC/AC neutral section	Cabin lights dim between the stations
Eungam	6	Loop through Yeokchon, Bulgwang, Dokbawi, Yeonsinnae, Gusan and back	Ride the loop back to Eungam
Gangdong	5	Line forks to Macheon and to Hanam; trains alternate	Branch shown on the departure board
Sindap	2 (Seongsu branch)	4-car branch trains; depot access line	Spring blossom by the screen doors
Kkachisan	2 (Sinjeong branch), 5	6-car branch terminus; Line 5 at B5 yet a 15-second transfer (2015)	New B5-to-street elevator (2025)
Hongik Univ.	2, AREX	Longest transfer in 2015 data: 355 m, Line 2 to AREX	The long walk to the AREX gates
Jongno 3-ga	1, 3, 5	Most exits (15) and 100 m moving walkway in 2004	Moving walkway on Line 3
Nowon	4, 7	Elevated-to-underground transfer; ranked last in 2014	Open-air Line 4 platform
Gimpo Airport	5, 9, AREX, Gimpo Goldline, Seohae	Korea’s first five-line transfer station (2023)	Five line colors on one sign
Wangsimni	2, 5, Gyeongui-Jungang, Suin-Bundang	Eastern Seoul’s four-line hub	Indoor garden on Line 5 B1
Sungshin Women’s Univ.	4	Widest platform gap in 2022 data, 28 cm	Automatic folding footboards
Sangdo	7	Korea’s first subway-station smart farm (2019)	Metro Farm and salad kiosk
Yeongdeungpo Market	5	Unused B2 and B4 built for a cancelled Line 10	Stair art and Big Mirror gallery
Dongjak	4, 9	Korea’s first road-and-subway bridge (1984)	Line 4 crossing the Han