first of all: Yeah, your first submission! Nice to have you on board :-)
Noise monitoring is definitely an exciting topic. There are several ways to do this.
The first question is what you have in mind? At which places do you want to make measurements? Are they accessible or thousands of kilometres away? Do you only want to determine the level (i.e. the volume) or do you also want to record an audio track? Would you like to measure above or below the surface of the water?
These are all questions that make it difficult to give you this one solution now.
You can find a quite good introduction here on the wiki page on Noise.
There are also a lot of apps that you can use, but this only works if you can move around on the spot and don't want to measure permanently in the middle of the sea ;-)
If you want to measure in the middle of the sea you probably have to deal with remote sensing. For this you can use microcontrollers (e.g. Arduinos or Raspberry Pi's) on which you play a program that stores and logs the measured values. If you have something like this in mind, I've linked some useful resources below.
I hope it helps you...
If you have any questions, I will be happy to help you.