I sat on a wooden chair on the balcony and listened to the hiss of the Caspian sea.

[alpacinou]

Can I use "hiss" to describe the sound of the sea/ocean?

Is this okay?

Later that evening, I sat on a wooden chair on the balcony and listened to the hiss of the Caspian sea.

 

[Tarheel]

If it sounds that way to you, fine.

 

[5jj]

It sounds unnaturally sinister to me.

 

[Phaedrus]

I sat on a wooden chair on the balcony and listened to the hiss of the Caspian sea.

If you have in mind a sound similar to what one hears when one opens a carbonated beverage, "fizz" is sometimes used for that sound. It can be used as a verb or as a noun. Unlike "hiss," "fizz" does not connote snakes or, by extension, the devil. You could say:

I sat on a wooden chair on the balcony and listend to the fizz of the Caspian.