Patches of read seawater are a natural phenomenon and not a cause for concern.
That’s the message from the Department of Environment, Food and Agriculture.
It follows concerns raised by the public after they were spotted in Laxey, Douglas and Ramsey.
Scientists have analysed samples of the water and confirmed the discolouration is caused by a type of algae.
Dr Kevin Kennington, Marine Monitoring Officer at the Government Laboratory, says: "This particular algae is non-toxic and regularly blooms during the summer months in the Irish Sea.
"This species has some interesting traits.
"For example it’s a plant that does not rely on photosynthesis to feed itself.
"Instead it engulfs other microscopic organisms to gain nourishment – so it’s a plant that eats other plants.
"The species name Noctiluca means ‘shines by night’ and the blooms of the organism around the Island may provide some spectacular bioluminescence along the shore line at night.
"The plants are able to emit light when agitated, possibly as a defence mechanism to stop themselves from being eaten.
"These light emitting properties are reflected in the species’ common names which are ‘Sea Sparkle’ or ‘Fire of the Sea’."
Whilst the alga is non-toxic it is possible that dense blooms will also congregate other organisms such as jellyfish.
The public are therefore advised to avoid swimming through patches of water that are clearly discoloured.