Don't know about Slovakia ,except that there is some boating there Cz.Rep. and Poland.Austria ,Slovenia,No. Italy and Croatia are a better bet ,that sounds scattered but remember the countries are small with awesome transportation systems.I found a site Mosabuam :: ...tidbits from Werner Moser and Manfred Moser
with a lot of pics of Austrian paddling and some in Slovenia they do other mountain activities as well,may have links to some Euro Mtn.Buzz.
If I were traveling in that part of the world Plitvice Lakes Natl. Park in Croatia would be at the top of my list,a sort of Agua Azul of the Balkans,definitely huckable falls and lake paddling in A Disneyesque setting featured in Vallhala or another TGR film.Coast of Croatia would also top list, beer tour of Czech Rep. and Bavaria too.