The speed of sound in water is about 1,482 meters per second, while the speed of sound in air is about 343 meters per second. This means that sound travels about four times faster in water than in air.
The density of water is about 1,000 kilograms per cubic meter, while the density of air is about 1.2 kilograms per cubic meter. This means that water is about 833 times denser than air.
The combination of the faster speed of sound and the higher density of water means that sound waves are much more compressed underwater. This results in a very muffled and distorted sound.
In addition, the high density of water makes it much more difficult for sound waves to travel through it. This means that the sound of a guitar underwater would be much quieter than the sound of a guitar in air.
Overall, the sound of a guitar underwater would be very different from how it sounds in air. It would be much more muffled, distorted, and quieter.