Swills,
The Infinium MAY make some noise as the waves roll by...it all depends on how you tune it. The thing about the Infinium is, it does not have salt water balanced out. You have to ground balance the unit AND adjust the discrimination knob ( which I believe adjusts the pulse delay) as well as the threshold to have it run smooth. The cool thing is, you can run it hot and have it false/chatter and it will be very sensitive to gold jewelry...and you can distinguish the falsing from an actual target.
I have found when hunting at the salt water beaches here in NJ, that running hot makes the unit a tad unstable, yet targets are clearly indentified over falses due to the repeatable hi/lo or lo/hi sound when sweeping over the target as well as it being louder. False signals as well as chatter are very faint beeps and blips and DO NOT repeat when sweeping in different directions. If you are in the water, you have to sweep slowly and sometimes wait for the unit to settle down.
The unit is not for everyone, but if you learn it, it's one heck of a beach unit.
There are only 3 problems I have with the Infinium:
1) The headphone connector..boy do I wish it was sturdier and Garrett made a heavy duty adapter so one can use other headphones.
2) You have to buy a straight shaft...the stock configuration is brutal
3) For beach use, the stock coil is no where near as good as the 10x14 mono...so you gotta get that coil !
But for performance, it's one of the BEST PI's out there in my opinion.
JC