Curses! I was just thinking this myself!
If fishing is added - and I don't even mind waiting for CE2 to do it, there needs to be a basic rod available from the TT so everyone can participate.
I don't like the idea of fishing probes - "fish finders" only add even more cost to an already expensive habit! Craftable rods is a fine idea though - with added distance and line strengths for higher "level" rods.
Boats - ok I guess, doubly so if they can only be used by their owners, but can carry passengers.
Among the potential - I can see additional textures and materials for crafting made from fishing, as well as future events and competitions.
Adding new fish mobs would be a relatively simply thing to do - since the base model (RipperSnappers) already exist along with viable animations that could easily be reused. I could remodel RS's into a dozen different fish in couple days (yes, I'm a Max monkey in my spare time).
Breathing Under Water:
This falls into the same category as jumping off of mountains (or the 4th floor balcony of Twin Peaks Mall) and walking away unharmed.... not really that big of deal to me. Though changing the underwater aspect adds the potential for a new set of Tools - air tanks, diving masks, flashlights, and depth gauges, as well at the potential for new clothing items (wet suits, flippers), as well as gives the possibility of making the Orca armors actually worth the effort to produce!
Flashlights:
Granted right now they'd be pretty useless - it's always a nice summer's day on Calypso. Granted this could be explained by a strange rotation, multiple suns, or any other astronomical anomaly, but we also know this is going to change with CE2 - we've already seen day and night pictures.
I'm also hoping that there be a difference between day and night in both the mobs and their behaviors. Some mobs might disappear at night to be replaced by others. While pre-existing mobs might change their behaviors - such as becoming more or less aggressive at night or by day.
Flashlights will become invaluable in this new environment.
And along those lines, the introduction of day and night also opens a window of opportunity for other new tools: Infra-red goggles, Night Vision goggles, and for hunters - infra-red and night-vision scopes.
It would also be a tremendous improvement to allow for the use of both day and night visibility and the use of camouflage in evading mobs. We have radar. Mobs should not. Animals and other less intelligent creatures should not just simply "know" where we are. They should have to see or otherwise sense us. I can accept some measure of "unnatural sensory perceptions" for some alien species - but all of them? C'mon, you can do better than that.
But I diverge a bit - I fully support the notion of fishing as a profession.
See my thread "New Professions" for more!
~Indigo
It all ties together sooo nice... 
