I have several islands in Minecraft, and I would like a simple way to walk from one island to another, that is, connect them together in some way.
I still don't want to prevent traveling by boat by filling up the ocean or something like that. I don't want to simply use a boat either, as it seems to be somewhat clumsy if I want to travel there often.
Best Answer
The simplest approach is to build a bridge.
You'll need to build up far enough (at least 3 blocks above water level) to ensure that you have clearance for your boat before building across.
You don't have to build mid stream supports as everything but gravel and sand are self supporting, but it might make building easier as you can build from both sides rather than having to creep to the end and add new blocks that way.
See this question on cantilevers for tricks and tips on this aspect.
If you don't want neutral mobs spawning on the bridge avoid dirt (unless it's completely disconnected from any existing grass). Cobblestone might be the best bet as you always have a surplus.
Make sure the bridge is well lit so hostile mobs don't spawn on it.
You could set up doors at either end to keep mobs off it too.