Longdong is defined by shore-entry reef and wall diving along the northern coast of Taiwan, with a remarkably rich cast of macro and cryptic life across its sites. The Chromodoris Nudibranch, Geometric Rainbow Dorid, Varicose Wart Slug, and Spanish Dancer appear consistently, making this a strong destination for nudibranch enthusiasts. Zebra Lionfish and Indian Lionfish are very commonly observed, alongside Pharaoh Cuttlefish, Snowflake Moray, and Pacific Trumpetfish. Sites range from beginner-friendly reefs like Longdong Bay #4 to intermediate walls such as Secret Garden. Local operators including I diving, 東北角潛水客棧, and 島嶼潛水 support the area.
Monthly water temperature across Longdong's sites, from satellite sea-surface data corrected for depth. The band shows the site-to-site spread.
Water temperatures are at their coolest from January through March, then climb steadily from late spring into a warm summer peak that holds through September before easing into autumn. The histogram of preferred dive dates points firmly toward late spring through summer as the most popular window, though conditions can suit diving from spring well into autumn. Exposure on shore entries may vary with swell, so checking local conditions before each dive is worthwhile.
13 more sites to explore
Water temperature around Longdong ranges from about 22°C in January to 28°C in July, based on satellite sea-temperature data for its dive sites.
In the warm season (about 28°C) a rash guard or 3mm shorty is comfortable in Longdong; in the coldest months (about 22°C) step up to a 3mm full suit.
Fin maps 15 sites in Longdong (14 scuba diving sites and 3 snorkelling spots, with some suited to both).
Across Longdong's dive sites, April, May, June, July, August and September are most often reported as the best months to visit.
Longdong is particularly strong for nudibranchs: the Chromodoris Nudibranch, Geometric Rainbow Dorid, Varicose Wart Slug, Ocellated Wart Slug, and Goniobranchus kuniei are all observation-backed and appear across a wide range of sites. The Spanish Dancer is also commonly sighted. Beyond nudibranchs, divers regularly encounter Zebra Lionfish, Indian Lionfish, Pharaoh Cuttlefish, Peacock Mantis Shrimp, Harlequin Shrimp, and Snowflake Moray.
Yes, several sites in Longdong are rated for beginners. Longdong Bay #4, for example, is a shore-entry reef and wall site explicitly classed as beginner-friendly, offering a broad depth range that allows less experienced divers to stay shallow while more confident divers explore deeper sections. Intermediate sites such as Secret Garden are also present, so the area accommodates a spread of experience levels.
The sites in Longdong are shore-entry dives, meaning you enter directly from land rather than from a boat. This makes logistics straightforward and keeps costs down, though rocky shoreline entries require attention to surge and swell conditions on the day. Local operators such as I diving, 東北角潛水客棧, and 島嶼潛水 are based in the area and can advise on current conditions and entry points.
Reef and wall diving are the defining site types in Longdong. Sites like Longdong Bay #4 combine both, offering a shallower reef section transitioning to a wall, while Secret Garden focuses on reef structure at intermediate depths. This mix means divers can choose between broad reef exploration and more dramatic vertical topography depending on their preference and certification level.
