So you're sure it's in Europe ? There are not many airports in europe that charge tax on entry. The only one that springs to mind is Tirana International Airport in Albania which levies a €10 fee, you can see mountains from the airport but no salt water.
As someone else mentioned Turkey does charge certain passport holders a fee when entering but it isn't a tax it's a visa charge, additionally, apart from Istanbul, it isn't in Europe. Ataturk Airport does have salt water but not much in the way of mountains.... Yerevan Airport in Armenia charges an exit tax on departure but doesn't have much in the way of salt water or mountains, also questionable as to whether it's Europe or not.