Mega-yachts are actually most environmental way to be bring million tourists to places to like Nordkapp. There has not been much complaints lately, because modern ships clean they sewage water and fuel exhausts.
What sources there could be? I remember that in the 1980s the indigineous Sami-population was whining about "pollution" of Porsanger fjord. Fish had diseases and crabs were dead. Upon investigation it was found out that cruiseships dump their toilets into the sea upon entering Honningsvåg, because the docking & dumping fees were too stiff. Nothing wrong with fishing nowadays.
And Norways coastal roadway is 5 times longer than the coastal ferry. That is an environmental issue if anything.