Let me start by saying that, by far, I really think the design and potential of Lemuria is fantastic. I think the stuff in it is interesting, and I think visually, it's one of the more fun and fascinating zones.
That said, it's absolute (literal) wet garbage.
Now, I know Lemuria has an important part in the game, ancient artifacts, civilization and civil war, monsters, ghosts, it's all very interesting. So why don't people go there to check it out? Well, let me share why I don't go and share some suggestions.
#1 - Travel is no fun
This, by far, is one of the biggest issues with Lemuria. Now, I can understand, hey, we're underwater, maybe some travel powers work better than others (Oh, hey, sorry Fire Flight, we're underwater, yeah. Too bad for you. You too, Swinging.) But the fact is, you rarely get any visible indication of your travel powers working or not. Last time I went, it was all swim swim swim, whether in my armored suit or my fire-winged Magician. I know I'm going faster because of my travel power, but ... seeing my armored hero doing the breast stroke looks weird.
Solution #1 - Show Power FX
This is the simplest solution, to have all viable powers show their effects. Things like the sundry forms of leaping and swinging are totally out of luck with this, but even showing the aura of some of the powers might be a nice change of pace. Some people suffer with this, but maybe you could give some consideration to people with other powers, like different animations or something ... but that pushes us toward solution #2.
Solution #2 - Stuff
Create different animations and effects for the underwater use of powers. Have flight users "torpedo" through the water with bubble or distortion effects, have people with swinging firing their guns forward instead of up, and have leapers give one powerful kick with a burst of high speed, rather than a continuous speed rate, while speedsters have a constant bubble effect around their feet to show the superfast kicks. This of course requires more work than #1, but would also be more satisfying to players.
Solution #3 - Quests
OK, so this is kind of a tangent, but HOW ARE WE BREATHING IN LEMURIA? Ok, let's assume everyone has a gadget, a spell, or mutant gills on demand. No, actually, let's not. IF you have Science / Arms / Mysticism at, say, 100 (let's be gentle with this since the current crafting system does not lend itself well to actual skill increases) you can skip the initial missions and just build stuff yourself on the ship by collecting ship items and building something. Otherwise, everyone starts with a slow swim, limited powers and a breath meter. Get some initial quests running to "waterproof" your powers and abilities (say three quests, gathering kelp or machine parts from wrecks and the like.) The quests can be done in any order, but allow for faster swim speeds (and FX like Solution #1 above,) full use of powers, and no need to breathe. This isn't a great solution, but it adds some meat as to why we have no "shrinkage" underwater.
#2 - That Dang Reef
OK, I love the Reef with all its caves and enemies hiding underneath shelves and the like, but what I hate is battling my way down one cave, then finding out that my entrance is in another cave, all the way on the other side of the reef OH WAIT NO, it's the one under this one I just now battled into and ... wait, where is this place anyway?!
Solution #1 - Cave Names
I'm sure the Lemurians know all these caves by heart. Why not pry the cave names from them and flash them on the screen when you enter and, just for fun, include the names in the mission briefings as well. This way, I don't have to trash a pile of Lemurians just for hanging out in the equivalent of a regressive fish-man coffee house.
Solution #2 - No More Caves
Seriously, do we really need, what, four caves? Five caves? Either have all the missions point to one cave or seriously, just put the zone entrance at the top of the cave and have done with it. Let those Lemurians congregate outside or just inside.
#3 - Lemuria Itself
Lemuria itself seems small, barely worth the time. It would be really nice to see missions inside Lemuria itself, like the domed cities. See the interesting architecture, maybe hang out with some of the non-regressed people under the sea. It would be nice to see something other than the Lemurian civil war, maybe providing some good will against enemies from the surface (like Argent exploiters or VIPER terrorists, or something.) It would seem there could be a lot of interesting mission arcs, but a lot of the missions just feel like "go here, kill x of y and come back."
Solution #1 - More missions!
Really, if you want people to come to Lemuria, it's the same solution as leveling characters. Provide alternate stories and alternate paths. Lemuria (like Vibora) seems to have an overabundance of mysticism and mystic enemies. It would behoove Lemuria to have as interesting and diverse a group of enemies as, say, Canada or the Desert. Granted, this is a lot of work, but I think this would really help out the zone in terms of playability.
You could even obviate the need for new underwater travel FX if you made some indoor missions in the different Lemurian domes.
Anyway those are my feelings; Aside from commenting on stuff like "other stuff needs fixing first," (which, I know, I know, there's any number of things to fix and improve) anyone share these ideas or have more?