# What might cause this "lake" to become red? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [April 6, 2026, 4:51pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068 "2026-04-06T16:51:31Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 6, 2026, 4:51pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/1 "2026-04-06T16:51:31Z")
Maybe it is just an artifact of the camera or maybe it is red? It’s on an island off the coast of Belize: 17.569237, -88.240367 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 6, 2026, 5:56pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/2 "2026-04-06T17:56:10Z")
I don’t know the answer, but here’s a direct map link: https://maps.google.com/maps?ll=17.569228,-88.240696&z=19&output=embed&dg=ntvb&q=17%C2%B034%2709.3%22N+88%C2%B014%2725.3%22W ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 6, 2026, 6:02pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/3 "2026-04-06T18:02:38Z")
> [@Chronos](#): > > I don’t know the answer, but here’s a direct map link: Thanks, Chronos. ---
**Author:** ![kenobi\_65](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kenobi_65/32/13178_2.png) [@kenobi\_65](https://boards.straightdope.com/u/kenobi_65)\ **Post date:** [April 6, 2026, 6:03pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/4 "2026-04-06T18:03:49Z")
As it doesn’t appear that that’s in an industrial area (so, not human-made pollution), and assuming that the satellite picture is representative of the lake’s actual color, it could be due to algae or bacteria, or soil runoff if there’s a high iron content in the local soil. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 6, 2026, 6:11pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/5 "2026-04-06T18:11:12Z")
> [@kenobi\_65](#): > > and assuming that the satellite picture is representative of the lake’s actual color FWIW, It also shows that red color on MapQuest maps./ ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [April 6, 2026, 6:25pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/6 "2026-04-06T18:25:40Z")
Usually red water is an algae bloom. [The Sea of Galilee turned red last year](https://www.jpost.com/environment-and-climate-change/article-863213) (and I think also in 2016). Red Tide is an example of this, but I don’t know that red tide applies to inland lakes. But I also can’t tell if the lake on that island is connected to the sea or what. Any body of water can have red algae, though. > **[Harmful algal bloom](https://en.wikipedia.org/wiki/Harmful_algal_bloom)** > > A harmful algal bloom (HAB), or excessive algae growth, sometimes called a red tide in marine environments, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, water deoxygenation, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen levels in natural waters, killing organisms in mar... I guess Belize’s east coast is also having an issue with [sargassum](https://www.belizetourismboard.org/tourism-resources/sargassum-resource/), but that is brown and from everything I see is just on sea coasts. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [April 6, 2026, 9:15pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/7 "2026-04-06T21:15:37Z")
The ground looks a weird color too? Is this possibly just something like the wavelength they image with to get through cloud cover or something? ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 6, 2026, 9:46pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/8 "2026-04-06T21:46:20Z")
Quoth AI (FWIW) : > [@](#): > > Google Maps and Earth primarily use high-resolution optical (visible light) and aerial imagery, not radar that penetrates clouds. To ensure clear images, Google stitches together thousands of images from satellites (like Landsat or SPOT) and aircraft taken when clouds are absent. When radar is used (e.g., for flood mapping via SAR, it uses microwave wavelengths—commonly L-band (15-30 cm) or X-band (~3 cm)—which can penetrate cloud cover, whereas optical sensors cannot. ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [April 6, 2026, 11:05pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/9 "2026-04-06T23:05:02Z")
It’s tannins leaching from the bark of red mangrove trees. You can see the same color on other islands in the vicinity, like here: [https://maps.app.goo.gl/iEjB7uAsMxicbnZw9](https://maps.app.goo.gl/iEjB7uAsMxicbnZw9) And this drone photo of a nearby cay that shows it’s a real color, not a Google Maps artifact. [![](https://i.viviun.net/i/1/l/277903/7AQNDF/1/E5A753/island-lots-for-sale-in-long-caye-placencia-stann-creek-belize.webp) ](https://i.viviun.net/i/1/l/277903/7AQNDF/1/E5A753/island-lots-for-sale-in-long-caye-placencia-stann-creek-belize.webp) [Here are some pictures of red mangroves in Florida.](https://www.wildsouthflorida.com/red.mangrove.html) > **[Mangrove Tannin: What is it? - Living Oceans Foundation](https://www.livingoceansfoundation.org/mangrove-tannin-what-is-it/)** > > Mangrove tannin is a compound is present throughout mangrove trees. It gives them their distinct colors and also provides many benefits. ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 6, 2026, 11:46pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/10 "2026-04-06T23:46:17Z")
Interesting! Thanks. ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [April 7, 2026, 2:01am UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/11 "2026-04-07T02:01:02Z")
> [@Lucas\_Jackson](#): > > from satellites (like Landsat or SPOT) and aircraft taken when clouds are absent Which in turn use near infrared to get the sharpest imaging of the coastline. FWIW I’ll also quote an AI here for some interesting bit - Claude. The red may be both algal bloom and false color! \>The underlying sources do capture NIR. Google Earth’s imagery comes from multiple satellites that are multispectral: ∙ Landsat 8/9 — includes NIR (Band 5) ∙ Sentinel-2 — includes NIR and red-edge bands ∙ Maxar satellites (WorldView-2/3, GeoEye-1) — include NIR\< \>Regarding the red lake: This area of Ambergris Caye has interior lagoons and brackish ponds that are known to experience algal blooms. Specifically: ∙ The northern caye has extensive mangrove wetlands with trapped, poorly-circulating water ∙ These lagoons are subject to cyanobacteria blooms, which produce strong NIR reflectance → red in false-color ∙ Nutrient loading from nearby development in San Pedro has been documented as a stressor on these interior water bodies Regarding the purplish land: Northern Ambergris Caye has seen significant land clearing for resort and residential development. The purplish signature fits: ∙ Sandy, cleared, or marl substrate typical of the caye ∙ Sparse dry-season vegetation ∙ Possibly compacted or disturbed ground from construction activity\< ---
**Author:** ![DSeid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dseid/32/20194_2.png) [@DSeid](https://boards.straightdope.com/u/DSeid)\ **Post date:** [April 7, 2026, 2:08am UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/12 "2026-04-07T02:08:36Z")
Oh this also from Claude. FWIW. \>Near-infrared (NIR, ~700–1000 nm) is almost entirely absorbed by water, so it’s used to cleanly delineate the water-land boundary — mangroves, shorelines, and island perimeters show up sharply.\< ---
**Author:** ![Apodder](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/apodder/32/17727_2.png) [@Apodder](https://boards.straightdope.com/u/Apodder)\ **Post date:** [April 7, 2026, 5:09pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/13 "2026-04-07T17:09:37Z")
Which, I assume, just uses the same satellite pics? ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [April 7, 2026, 5:32pm UTC](https://boards.straightdope.com/t/what-might-cause-this-lake-to-become-red/1029068/14 "2026-04-07T17:32:45Z")
They did not look the same to me.