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Your guide to the famous Four Sea Arches of Hong Kong

By Beverly Ngai 29 July 2021 | Last Updated 16 December 2021

Header image courtesy of @vvvincyli (via Instagram)

Part of the Hong Kong UNESCO Global Geopark, the archipelago of islands off the southern coast of Sai Kung is brimming with world-class geological formations. From precipitous cliffs to rocky sea stacks, there is a great deal to marvel at, but emerging most prominently from the cornucopia of treasures are the famed Four Sea Arches.

As these prized arched landforms are located further out at sea, where wind and waves unleash their full power, it takes an intrepid soul to journey out and explore their rugged beauty. To boost your confidence, we have done much of the legwork for you and broken down what you need to know about visiting the Four Sea Arches of Hong Kong.

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Photo: @bowingkwchan (via Instagram)

Overview & fast facts

Spread across four different islands, the famous Four Sea Arches consists of Tiu Chung Cave, Lam Wan Kok Cave, Sha Tong Hau Cave, Wong Chau Kok Cave. The former is located on Tiu Chung Chau (also known as Jin Island), while the latter three are found within the Ung Kong Island Group—a core geological zone of hexagonal rock columns. A bit of a misnomer, these wave-sculpted wonders are not technically “caves,” but sea arches, wherein the coastal erosion extends all the way through the excavated rocky headland, creating an open and impossibly photogenic passageway.

Formed from a supervolcano that erupted in the Sai Kung area over 140 million years ago and sculpted over time by the brute force of the sea, the Four Sea Arches are not only awe-inspiring in their magnificence, but they also draw much attention due to their unique geology. Extremely rare with the type of acidic rhyolitic volcanic rock that they come in, the arches boast spectacular hexagonal columns that showcase mesmerising patterns.

You will find these four colossal sea arches jutting out from the east-facing side of outlying islands, where they are exposed to the open sea with little natural barriers. Such locations are more susceptible to rough currents, so you will have to plan your trip closely around the weather conditions. The best time to visit is in the summertime when the sea is calmer and relatively safer to venture out into.

How to get around

With no regular ferry service to the islands, the most accessible way of exploring the famous Four Sea Arches is by chartered boat. Dauntless adventurers can also opt to get around by kayak, but the undertaking requires a high level of physical fitness and is only recommended for very experienced kayakers.

Local sight-seeing boat tours are available as well, as guided tours organised by partners of the Hong Kong UNESCO Geopark make it possible for you to see all four sea arches in one go. However, if you prefer scouting out all the little gems that each island has to offer at a leisurely pace, then you are better off exploring one island at a time, or at the very least, splitting it into two trips.

To Tiu Chung Chau:

The logical way of doing so is to make separate visits to the sea arch in Tiu Chung Chau and those in the Ung Kong Group respectively. As Tiu Chung Chau is the largest of the islands housing the Four Sea Arches and is replete with natural wonders, you could easily fill a day with sight-seeing and activities there. From Sai Kung Pier, a speedboat will bring you to Tiu Chung Chau in around 20 minutes.

To Ung Kong Island Group:

Located in closer proximity to one another, the sea arches within the Ung Kong Island Group—Lam Wan Kok Cave, Sha Tong Hau Cave, and Wong Chau Kok Cave —can be toured together. Join a local boat tour or arrange a private speedboat—either way, you can expect a half an hour boat ride to get to Ung Kong Group from Sai Kung Pier. Alternatively, if you are kayaking there, begin from Pak Lap Wan instead and make your way south to Wang Chau, Basalt Island, and Bluff Island. This will save you several hours’ worth of paddling!

What to bring

Getting offshore to explore the islands is not for the aquaphobic or faint-hearted. If you plan on doing so, you should be equipped with proper swimming and hiking gear—this includes both water and trekking shoes, swimwear, a personal flotation device, a waterproof bag, and gloves to help you get up and down rugged rocky surfaces. Given that there is very little shade on the islands, adequate sun protection is also a must.

You will not find any tourist facilities or signs of civilisation on the islands, so make sure to pack plenty of water and snacks as well to keep your body fuelled and hydrated.

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Wang Chau Kok Cave

Wang Chau (橫洲) may be the smallest island of the Ung Kong Group, but it is home to one of the biggest sea arches in Hong Kong. Fronting the endless blue of the South China Sea on the eastern edge of the island, the mighty Wang Chau Kok Cave (橫洲角洞) rises over 20 metres tall and measures around 10 metres in length. One feels wonderstruck when coming face to face with the rocky behemoth and its otherworldly presence!

Its unique appearance has earned it the amusing nickname of “Moon Tooth Cave” (月牙洞). Curved and tapered at both ends, the opening vaguely resembles a crescent moon, while the inner walls are lined with jagged, teeth-like fissures from where the rocks’ columnar joints are exposed to the waves. As the passageway at the base is rather narrow and rugged, extra caution is called for should you attempt to paddle through it.

Lam Wan Kok Cave

Located southeast of Wang Chau is Basalt Island and its crowning glory, Lam Wan Kok Cave (欖灣角洞)—a 16-metre sea arch dramatically shaped like a straight-edged blade, adding to the sense of imposing grandeur and making for a first-rate photographic subject. As if made for Instagram itself, there is a rugged outcrop conveniently jutting out in front of the archway’s entrance, which you can mount to pose for the perfect picture.

Basalt Island is a place of many delights, so spare some time to discover its other sea-crafted geological treasures, such as the twin sea caves, and the Sea Palace cavern located on the northeast side of the island. For the thrill-seekers amongst you, brace yourself some of Hong Kong’s most premier scuba diving, bouldering, and coasteering fun! Click here to read our full guide to Basalt Island.

Sha Tau Hau Cave

While the U-shaped bay on the northern part of Bluff Island—or Sha Tong Hau Shan (沙塘口山)—is rife with tropical marine life and sugar-soft sandy shores, go around to the opposite side of the island and you are met with a markedly different, yet equally alluring scenery: a bare swathe of ancient volcanic rock, its rust-red colour and craggy contours faintly resembling that of our neighbouring planet.

Against the landscape of towering hexagonal rock columns, Sha Tau Hau Cave (沙塘口洞) sits like a slit in the wall, the narrow, rectangular entrance just wide enough to admit the passage of one kayak at a time. Passing through the shadowy portal closely bounded by rocky walls, you will feel as if you’re in a secret tunnel!

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Tiu Chung Cave

Tiu Chung Chau (吊鐘洲)—or “Hanging Bell Island,” if you are translating directly from Cantonese—is named after the remarkable 30-metre bell-shaped sea arch found on the southern end of the island. Whether admired from near or far, the arched rock formation of Tiu Chung Cave (吊鐘拱門) is nothing short of nature’s finest artwork. Up-close, the contrasting textures and hues from the lush green foliage, shallow, rock-strewn waters, and the arch’s high and wide opening offers a great diversity of photo ops.

For a more encompassing field of vision, climb up to the peak of Jin Island and capture a shot of the entire headland and its picturesque surroundings. From here, the view is said to look like a giant wagging goldfish splashing playfully in a pool of shimmering waters!

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Beverly Ngai


A wanderer, chronic overthinker, and baking enthusiast, Beverly spent much of her childhood in the United States before moving to Hong Kong at age 11 and making the sparkling city her home. In her natural habitat, she can be found baking up a storm in her kitchen, journalling at a café, or scrolling through OpenRice deciding on her next meal.