Tales of the Bioluminescent Sea:

Chasing the “Blue Tears” of Matsu

Joanna Wang　/　photos courtesy of Lienchiang County Government

May 2026

中文

photo by Wang Wenzhong

Between April and June each year, the most common question locals on the Matsu Islands are asked is: “Will there be tears tonight?”

These “tears” refer to the now-famous phenomenon known as “Blue Tears.” This glowing marine spectacle, once listed by CNN as one of the world’s top 15 natural scenic wonders, has added a touch of nocturnal romance to an archipelago formerly known as a frontline military outpost.

photo by Wang Changlin

Underwater fireflies

Scientific studies indicate that Blue Tears are primarily caused by a single-celled plankton commonly known as sea sparkle (Noctiluca scintillans). These organisms do not emit light spontaneously; they only produce a faint blue or cyan glow when physically disturbed by crashing waves, swimming fish, or the wake of a boat.

Furthermore, each flash of bioluminescence lasts for less than a second. As a result, the Blue Tears you see with the naked eye are rarely as intense or dazzling as they appear in long-exposure photographs. Instead, they resemble underwater fireflies, flickering briefly with an elusive, mysterious charm.

photo by Wang Tingyu

Ancient tides and modern viral wonder

Locals recall that this phenomenon has long been a natural occurrence on the islands. In the past, fishermen called it “dingxiang water” (silver-stripe round herring water), as the massive blooms of Noctiluca often signaled schools of these small fish gathering to feed. It was not until over a decade ago, when photography enthusiasts and stationed military conscripts began sharing images of the glowing night sea on social media, that this maritime marvel truly captured the public’s imagination.

The frequent appearance of Blue Tears in Matsu is closely tied to the archipelago’s location near the estuary of the Min River. Every spring and summer, the river discharges abundant nutrients into the sea, triggering a massive multiplication of diatoms, which serve as the primary food source for the bioluminescent plankton. Consequently, while Taiwan’s main island is completely surrounded by the ocean, few places offer the near-annual guarantee of Blue Tears found in Matsu.

photo by Wu Shihui

The art of the chase: Timing, patience, and serendipity

From Nangan and Beigan to Dongyin and Juguang, each island in the Matsu archipelago offers a unique vantage point for “tear-chasing.” Some visitors wait on sandy beaches for the glowing “tear waves” to wash ashore, while others splash water by the piers to coax out the light, or take boats out to sea to watch the hull carve a brilliant blue wake through the darkness.

The Beihai Tunnel on Nangan is widely considered one of the most accessible spots for beginners. The calm, stable waters inside the wartime tunnel create an ideal environment for the organisms to thrive. However, because there are no natural waves within the cavern, visitors must gently splash the water themselves to awaken the speckles of blue light, which dance across the surface like a reflection of the starry night sky.

That said, witnessing the Blue Tears is never a guaranteed prospect. Tides, water temperature, wind direction, and even the brightness of the moonlight all play crucial roles. Every evening, enthusiastic tear-chasers exchange intelligence on social media: “Is the water clear today?” “Where is the wind weakest?” “Are we approaching high tide?” Much like chasing the aurora borealis, spotting the Blue Tears requires the perfect alignment of timing, location, and a little bit of luck.

photo by You Yikun

From phenomenon to brand

To ensure this natural wonder is no longer strictly limited by season and weather, Matsu established the Matsu Blue Tear Ecological Museum in 2018. By collaborating with National Taiwan Ocean University on cultivation techniques, the museum allows visitors to observe the bioluminescent phenomenon up close, year-round.

In recent years, the Lienchiang County Government has actively partnered with private enterprises to promote Blue Tears tourism, seamlessly integrating it with the region’s traditional Eastern Min (Mindong) settlements, military heritage, local delicacies, and eco-tourism. For Matsu, the Blue Tears have evolved from a mere natural landscape into a vital brand for sustainable tourism development.

photo by Kent Chuang

A pact with the ocean

The captivating allure of the Blue Tears perhaps lies precisely in their unpredictability. You might wait an entire night in the dark, only to find the sea stubbornly silent; or you might casually turn around, only to be ambushed by a sudden, breathtaking burst of fluorescence. The uncertainty and the waiting transform the chase into a silent pact made with nature.

A trip to Matsu is not just about checking a glowing blue sea off your bucket list. It is an invitation to slow down and truly connect with the islands, the ocean, and the stars. After all, it is the fleeting, ephemeral beauties in life that are often the most unforgettable.