I'm no expert having only been to Alaska for the first time this past May, but we did a variety of excursions, lots of walking through the towns and hiked to the Mendenhall Glacier and we took hiking boots along with our tennis shoes and some other casual shoes (way too many pairs of shoes!!), and still wore tennis shoes the entire time we were off the ship. I would guess that if you do a flightseeing tour of the glaciers where you land on the glacier itself, Ugg boots may be needed, but a lot of the tour companies provide foot gear if special boots are needed. Other than that, even at the end of May, the only snow we encountered was on our 4x4 Jeef safari to the Yukon. DH did manage to get his jeep stuck in the snow, but other than that and some water run-off from the snow, we did not need any kind of boots. We never did get wet feet. A little dirty on the dog-sledding to the musher's camp, but still needed only our tennis shoes. Good advice from PeterC to have an extra pair in case your shoes do get wet. We had light rain only our first day in port at Sitka - other than that, dry the entire time. Sudden short rain showers are to be expected, though, and it would be miserable for you if you did not have a dry pair of shoes to wear. Especially in Ketchikan, where we did a lot of walking, our tennis shoes were all we needed. The weather was a lot warmer than we expected at the end of May, and I would imagine now that boots would probably not be needed. As everyone who gives advice will tell you, dress in layers! We wore fleece over long-sleeved pullover tops over t-shirts and took waterproof jackets with us everywhere, and the fleece came off, hardly wore the jackets, believe me, we were plenty overdressed! We did dress warmly when we sailed through the glaciers - the air coming off of the glaciers is cold and I am glad I had my scarf and gloves - but other than that, we won't take nearly as much stuff the next time we go!