Exploring fjords from a boat is a fantastic idea! It is truly one of the best ways to experience the scale and beauty of nature. But at the same time, I would recommend not to forget about preparing for unforeseen situations. The weather in such places can change instantly, and it would be good to have not only life jackets, but also other emergency equipment on hand. For example, signal lights, portable radios, a first aid kit - everything that will help in an emergency. Recently I came across a site with a useful selection of such devices: https://gaelixmarineservice.com/safety/emergency-equipment-devices/. Everything is very clear and to the point there. If you are going on the water, especially to new places, be sure to think about the safety issue.