I plan to make an iron farm plenty of blocks away from my base- including over the ocean. I'm aware of methods such as water and ice, but for one I lack a pickaxe to grab ice blocks, and second I'm worried about them despawning. I'm aware of Nether transportation, but I've heard you have to be in the Nether for it to go through. I'd like to know what you'd suggest for transporting items.
My idea was a mix of the first idea alongside hoppers/droppers. In order: Water source, 6-7 blocks (Water goes this way), Hopper (Water isn't over this), Dropper, and possibly a Sign. The logic behind this was that items would reset their despawn counter when put into a dropper or the like. So even if it was close to the counter's end and it entered a hopper, then that means the counter would be set back to 5 or so minutes.
What do you call a long distance? Items are de-spawning after 5 minutes. Do a water street. it is very fast. Don't forget the packed Ice! And if it needs longer than 5 minutes just put a hopper-dropper system. Be sure to have all the way in a ticking area, otherwise nothing will happen.