Simple wireless LED and remote

[Hunter4]

Hi guys,

I'm really new to electronics and I'm looking for help in making a design I have.

I started scuba diving recently and have found it difficult to attract the attention of my partner whilst under the water and facing away from one another. The solution I have come to is the implication of a set of wireless transmitters and receivers that work in a similar way to highly simplified walkie-talkies i.e. person 1 presses a button, a signal is transmitted, person 2 receives the signal and an led is switched on, person 1 releases the button, led goes off.

I know this may be a simple circuit to create but as I said, I have very little knowledge of electronics. The requirements for this system are: the remote and the receiver/led must be compact (as small as possible), self contained (runs on 3V, button cell batteries), is waterproof but can be unsealed to change batteries, the signal is omnidirectional (person 1 does not need to be pointing directly at person 2 like ir tv remote controls) and have a range of at least 100 yards.

If someone would be able to let me know the best pieces to use or has any suggestions, I would be very grateful.

Thanks for your help in advance.