Busan

Busan is long rather than dense. The city runs about thirty kilometres along the coast, and the two ends behave like different places: Seomyeon and Nampo in the west hold the markets, the old port and the hillside houses of Gamcheon, while Haeundae and Gwangalli in the east are beaches, towers and the good evening view back at the bridge. The subway connects them in forty minutes, but doing both properly in one day means riding it four times.

The market is the argument for the western half. Jagalchi is a working fish market where you buy downstairs and have it cooked upstairs, and it is busiest and best in the morning. Gamcheon, the painted village on the hillside above the port, is genuinely residential — go early, keep to the marked routes and treat the alleys as somebody's street rather than a set.

Haedong Yonggungsa sits on the rocks north-east of the city and is the one sight worth an early start. It opens around sunrise and fills with coaches by mid-morning, so reaching it near opening and then staying east for the rest of the day — Haeundae, the coastal walk, Gwangalli in the evening — is the version of the day that works.

Busan is two hours and forty minutes from Seoul by KTX, which makes it the obvious end point of a southern route rather than a detour. It also has an international airport with short flights to Jeju, so a mainland-then-island trip can finish here instead of doubling back to Seoul.