Why can sound travel much farther through seawater than visible light?

Seawater is significantly more transparent to sound than it is to light, which is why acoustic waves can travel much farther underwater.1

The primary reasons for this difference include:

• Attenuation and Absorption: Visible light is rapidly attenuated in seawater through absorption by water molecules, dissolved substances, and suspended particulates. While some blue-green wavelengths can penetrate to certain depths, most light is absorbed or scattered relatively quickly. In contrast, sound experiences much lower attenuation in liquids than in gases, allowing it to propagate over vast distances.23
• Propagation Mechanisms: Sound travels through water as a series of pressure disturbances. Because water is only slightly compressible, it is an excellent conductor of sound. Furthermore, sound waves can become trapped in the SOFAR (sound fixing and ranging) channel—a zone of minimum sound speed at depths of approximately 1,000 meters—where refraction prevents the sound from dispersing in three directions, enabling it to travel for great distances.41
• Electromagnetic Limitations: Electromagnetic radiation, which includes visible light, does not propagate well underwater, making acoustic techniques like sonar the preferred method for long-range underwater detection and communication.5