Seoul's Han River parks stretch across long sections of the city, so the nearest restroom or facility may not be obvious from the name of the park alone. The Seoul Metropolitan Government currently recommends Smart Seoul Map's Hangang Park Guide for finding practical facilities from your location.
The city says the Hangang Park Guide can show restrooms, bicycle access points, parking and leisure, culture and tourism facilities. It is web-based: you do not need to download an app or log in to use the guide.
This is most useful when your plan involves a long riverside walk, cycling, traveling with children, or meeting someone at a large park where facilities are spread out. Open the map when you are near the river rather than relying on an old static image.
Accessibility varies by facility and route. If you specifically need an accessible toilet or step-free path, check the displayed facility details and the actual route before setting out; a map icon does not prove the whole journey is barrier-free.
For festivals or large events, temporary toilets or access changes may be added separately, so also check the event notice when relevant.