can i go agaonst most of the posts here and suggest if terrestrial is to be the main use then an upright & correct image will be of high importance..i think there are two good options
1. high powered binos, something like 15x70 or 20x80
2. a spotting scope, goto andrews
http://www.andrewscom.com.au/site-section-10.htm then the long perng section.. they have a 80mm spotting scope which is waterproof & has adjustable zoom.
the only thing left to do in either case is get a decent tripod, andrews have generic chinese ones which are pretty good - stick with a known brand as cheap ones will falll over / wobble