Flares cannot be used underwater? What?

[The Militant Penguin Front]

So yeah... I have flares but when I click I just get red text saying cannot be used underwater.... so what's the point of these paper weights?

[maximummax]

you should be able to use them, could you please make a video of how it works for you?
you can also try to put it in your quick inventory slot, and then press the key to drag it out, and then left mouse click to activate it

[SicSid1980]

We used one underwater but it did very little in terms of illumination.