Why?
1. Although the view range works great on land, I feel like it's unreasonably small in the ocean. To find something in a deep ocean you need to stumble right into it with your face, especially since local resources and other stuff are so few and far between in the water. That brings me to the next point:
2. As much as I like exploring the world and sailing the oceans - finding anything other than islands is nearly impossible there. You can be living right next to kelp island and never know about it just because you always swim just a little north or south from it.
3. It will give another use of the hard (or rather annoying) glass-making process
4. It will encourage people to explore the world and oceans around them
5. It will help us locate those hidden thingswalls among the countless islands
Now, I don't feel like making it just increase the view range would be a good (and easily implemented) idea, so the way it should work in my opinion is as follows:
1. Make it an item you need to hold in hands and be usable with a click, as well add a small "searching" time when using it, during which you'll have to stand still for ~10-20 seconds. That is to make it actually be used by people intentionally exploring the certain area, instead of being a tool you click every X tiles. Also only being usable in the deeper ocean.
2. After the use it should show a direction of a random "point of interest" around the character (say, 250 tiles) that still haven't been seen by the user. It can be local resources or thingswalls.
May also add a flavor experience event once in a while.
Now, I'm in doubt about adding an ability to track whales/orcas or maybe even other ships with it. That would actually help oceans feel more "alive", but it'd mean there has to be a restriction on telescope use. Either per*exp check (which can arguably be abused pretty easily) or making it a separate option that has an experience cost. The problem with that feature would be the possible encouragement of people to place "watching alts" and check them from time to time. Plus considering the spawning-despawning of animals in sea - that also may be stoped by technical limitations.
