The standard Jeju advice is "rent a car," but plenty of visitors cannot — no IDP, under the age limit, or just not comfortable driving abroad. Jeju without a car is doable; it just requires honest planning. Here is the real picture.
The Bus Network
Jeju's buses are better than their reputation but slower than you hope. The key routes: the 201 and 211 run the east coast (Jeju City–Seongsan, about 90 minutes), the 281 crosses the island to Seogwipo past the Seongpanak Hallasan trailhead, and the 202 covers the west coast. The airport limousine 800/801 runs to Seogwipo via Jungmun. Fares are 1,200–3,000 KRW with a T-money card — your Seoul card works. The catch: frequencies run 20–60 minutes, service thins after 20:00, and many trailheads and beaches sit a walk or a taxi hop from the nearest stop. Naver Map is essential — it shows real-time bus positions.
The Day-Tour Circuit
The pragmatic move: base in Jeju City or Seogwipo and book the hop-on day tours. The "East Course" and "West/South Course" bus tours (sold on Klook, KKday, and through guesthouses, roughly 30,000–60,000 KRW) hit the major sights — Ilchulbong, Manjanggul, the waterfalls, Jusangjeolli — with an hour or two at each. You lose flexibility but gain coverage: a tour day sees more than a DIY bus day, guaranteed.
Taxis and the Hybrid Approach
Jeju taxis are reasonable for hops — Seongsan to Seopjikoji runs about 8,000 KRW, and Kakao T works on the island. The smart hybrid: buses for the long cross-island legs, taxis for the last-mile gaps. A full taxi day charter (4–5 hours) negotiates around 150,000–200,000 KRW — worth it for a group.
What You Will Miss
Be honest with yourself: without a car you will not catch the Ilchulbong sunrise unless you sleep in Seongsan, the west-coast cafe strip is awkward, and spontaneous stops at random oreum and coastal pullouts — half of Jeju's charm — mostly disappear. Plan fewer sights per day, cluster by coast, and book one guided day for the far-flung spots. It works; it is just a different, slower Jeju.