Need help with sealing wood cabinet

[vader]

Finally have my cabinet built and stained, but need to seal it with some kind of polyurethane.  I'm looking to have a nice medium gloss to it and need for it to be able to stand up to saltwater since my fish tank will be near it.  I used Minwax gel stain ( honey oak ) and put 5 coats on.  Came out good, now need to protect it.

What does everyone recommend and best way to apply it.

Thanks

[WaRpEd]

Since you used Minwax stain I'd stay with their Polyurethane.
A good quality brush is all you will need to apply the poly.
Make sure to use a tackcloth and a dust free well ventilated area.
The Marine poly does hold up better in wet enviroments than the water based.
Thin coats of poly are prefered to a heavy coat which can run or sag.
Take your time time and you'll get good results.
Good luck with your project and post some pics.
Cheers