With the help of some carbon nanotubes, Aquaman just added a new ability to a repertoire that consisted of talking to fish and swimming real fast: becoming invisible. A research project from IOP Science uses carbon nanotubes, which possess an extremely high heat transfer ability, to produce photothermal deflection. You may know it better as the mirage effect: when light waves move from an area of colder air into a dramatically hotter area, they bend away. The more pronounced the temperature gradient, the stronger the effect.
Since the carbon nanotubes can be heated to 2500 degrees Kelvin, they produce a dramatic distortion of the liquid around them. All Aquaman needs is a carbon nanotube cloak and he'll be impossible to spot.
The research white paper explains that "water has an unusually high thermal conductivity and very low temperature coefﬁcient of refractive index which makes water unattractive for achieving high photothermal deﬂection." However, they're better at thermal exchange than gases. The point is, you could have an invisibility cloak of your own one day that works in the open air and sunlight, no gills required.