Once you can fish in the underworld, I found this spot. It just requires the ability to teleport (and a non-mage can do it with scrolls bought from an NPC that sells 3rd circle - humans can even attempt it at about a 25% chance of success just casting from a book).
1. Go to A.
2. Teleport to B.
3. Dismount off your pack beetle (tag-along pack animals don't work because of how teleport works)
4. There's about 2-4 spots to fish there, and you can even use crustacean traps there (can place about 8-10 if spaced right).
5. fish until the spots you can cast to all run out, then remount.
6. After remounting, teleport to C and dismount.
7. Under the bridge there's 2 more areas (not as good) to fish at, but by the time you do them the areas around B will respawn fish.
8. Remount, teleport back to B, and repeat steps 3-8 until the beetle's full and so is your pack.
9. Recall out, or teleport back to bridge area A from B.
The area itself is safe from spawn (the worst you'll see once there is a goblin if someone lures it that way), but to get to it you have to run through the worms and blood eles from the Underground entrance, take the teleporter over, then back on the bridge. Gargoyles can fly over, but they don't get to use a pack animal.
I got almost all my Fishing gains from 106-120 there.
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