In brief
News reports place green algae on White Beach in the dry season, usually the first quarter of the year and rising from late November, and ABS-CBN reported the shoreline covered on 19 February 2025. A satellite study of the 2018 closure year found its algae indices at their maximum “during early wet season” instead.
- Rappler reported in 2022 that blooms usually occur in the first quarter, with more cover in late November and December1.
- Inquirer reported in April 2019 that summer is when blooms are expected2.
- The satellite study measured two indices before, during and after the 2018 closure and called the seasonal pattern “possible”4.
- Causes are disputed: a former environment secretary blamed sewage in 2015, while the island’s management group called it a natural yearly phenomenon in 202221.
- No published result of the DENR and University of the Philippines study into why blooms recur appears in the sources used here.
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Where to book Current rates across the island.
Frequently Asked Questions
When is the green algae season in Boracay?
News reports place it in the dry season: usually the first quarter of the year, with more cover from late November1, and in February 20253. A satellite study found a maximum in the early wet season of 20184.
What causes the green algae on White Beach?
Officials have named sewage and nutrient pollution2, untreated wastewater and detergents5; the island’s management group called it a natural yearly event1. Why it recurs was put to a DENR and university study in 2022, and no result appears in the sources used here5.
Is Boracay's algae harmful?
The island’s management group called it non-toxic in 20221. A DOST scientist said it “should be taken seriously” as a sign of pollution1.
Does algae make the sand white?
No. DOST-PNRI’s Raymond Sucgang said algae is not why the sand is white, and a local belief that it helps create fine sand was reported without support1.
Is the water safe to swim in when algae is present?
The swimming standard is 100 MPN per 100 mL, and the front beach measured 11 in February 202225. The sources used here contain no later reading, so check current DENR-EMB Region 6 and BIARMG advisories.
Is the algae worse on one part of White Beach?
No source maps it by station. Residents harvest at the less populated back end1, and a small remaining bloom was reported at the northern end in 20192.
The detail
If you are choosing travel dates, this page sets out what is on record about when green algae, called lumot locally, covers parts of the shoreline, and what officials, scientists and local groups say causes it. The wider monsoon picture is in When to Go to Boracay.
The short answer
| If you are… | Then… |
|---|---|
| Travelling between December and May | Algae has been reported in these months in 2019, 2022 and 2025123. Check current advisories before you book a beach-only stay. |
| Travelling between June and November | A satellite study found its algae indices highest in the early wet season of 20184. Rappler also noted rising cover from late November1. |
| Worried about swimming safety | The management group called the algae non-toxic in 2022, while a DOST scientist said it should be taken seriously1. Neither claim is a swimming advisory; check the latest DENR-EMB Region 6 and BIARMG notices. |
When it has been reported
| Source | Date | What it says |
|---|---|---|
| Rappler | 24 November 2022 | The bloom “usually occurs in Boracay at the first quarter of the year, a dry period”, with increasing cover in late November and December; the Ati see the green clumps as a sign of summer1 |
| Inquirer | April 2019 | “Summer is when algal blooms are expected in Boracay”2 |
| ABS-CBN | 20 February 2025 | The shoreline was covered with green algae on 19 February 2025; blooms are common “during the dry season”3 |
| ISPRS Archives (peer-reviewed) | 23 December 2019 | Satellite indices were at their maximum “during early wet season”4 |
By PAGASA’s national calendar the dry season runs from December to May and the rainy season from June to November6.
Sources disagree Three news reports tie the bloom to the dry season123. A University of the Philippines study of satellite images from before the 2018 closure to the reopening found its Normalized Difference Vegetation Index (NDVI) and Floating Algae Index (FAI) fell in the first month of closure, in the late dry season, “increased to their maximum during early wet season” and fell again at reopening4. The abstract gives no months and covers one unusual year, and its authors call the seasonal effect “possible”. Plan around the news reports: assume algae can appear from about December to May in calm seas, and do not assume June to November is free of it.
Where on the beach
No source maps the algae by station. Rappler reported that residents harvest it at the “back end”, the less populated side, not the front beach1. Inquirer reported in 2019 that after a cleanup a bloom remained “in a small area at the northern end of the island”, described as less thick than before2. For where the stations are, see Boracay Areas Compared.
What causes it, as stated
| Who | When | Statement |
|---|---|---|
| Ramon Paje, then Environment Secretary | 2015 | The bloom indicates “poor waste management, with sewage being dumped into the waters”2 |
| DENR, citing the Global Coral Reef Alliance | 2015 | Green algae in the calm season are “a strong indicator of very high nutrient pollution”, typically found near sewage outfalls; they die back in the rough season because waves dilute nutrients and become visible again in the next calm season2 |
| DENR Region 6 | 2022 | Found untreated wastewater causing blooms and named soaps and detergents as suspects; the acting secretary asked the DENR and the University of the Philippines Marine Science Institute to study why blooms recur despite lower coliform levels5 |
| Martin Joseph Despi, Boracay Inter-Agency Rehabilitation and Management Group general manager | March 2022 | Algae is “a natural phenomenon that occurs yearly” that is non-toxic and not a cause for concern1 |
| Raymond Sucgang, DOST-PNRI | 2022 | “Green algae should be taken seriously”; harvesting for fish feed or fertiliser does not fix the pollution roots1 |
Sucgang also said algae is not why the sand is white; a local belief that it helps create fine white sand was reported but not supported1. The women’s cooperative reported a buyer offering PHP 5 a kilo for dried algae, with a member able to gather about 100 kg a day1.
No published result of the DENR and University of the Philippines study appears in the sources used here.
Water quality figures on record
- The standard for areas used for swimming is 100 MPN per 100 mL (most probable number of coliform bacteria)2.
- The environment secretary reported in April 2019 that the highest reading “in recent months” was 40 MPN per 100 mL2.
- As of February 2022 the front beach measured 11 MPN per 100 mL5.
- The satellite paper cites a fall from 1 million to 18.1 MPN per 100 mL after the rehabilitation4.
The sources used here contain no reading after 2022. Low coliform readings and algae blooms have been reported together, which is why the 2022 study was requested5.
Related Articles
Sources (6)
- Boon or bane? Boracay’s algal bloom can provide income to poor local folk — Rappler, 24 November 2022. Accessed 2026-10-03.
- Boracay waters safe for swimmers–DENR — Philippine Daily Inquirer, 27 April 2019. Accessed 2026-10-03.
- Boracay shoreline covered with green algae — ABS-CBN News, 20 February 2025. Accessed 2026-10-03.
- Detection of algal bloom in the coastal waters of Boracay, Philippines using normalized difference vegetation index (NDVI) and floating algae index (FAI) — Visitacion et al., ISPRS Archives, 23 December 2019. Accessed 2026-10-03.
- DENR to create team to probe Boracay’s algal bloom — Journal News Online, 7 April 2022. Accessed 2026-10-03.
- Climate of the Philippines — PAGASA. Accessed 2026-10-03.