Controllerless Networks

I checked spec sheet for IAP200 series and it does show up to 95% non-condensing for Humidity under environmental section. Can it be used for indoor high humidity environment, like a indoor swimming pool?

BTW, IAP204 with two external dipole antennas vis IAP205, do they have big difference performance/coverage wise?

You should consider an "outdoor" AP for that environment.  When you say "like" a swimming pool, what environment are you  talking about?  

The performance would be same, but the coverage would be different with external antennas.

Note you would likely do better with an IAP-228 or even a 275 if it's a typical indoor commercial pool where there are high chlorine particulates in the air. Chlorine is not exactly the greatest thing to expose ethernet connectors and cabling to (let alone plastics, etc). The 228 would put the ethernet cable behind a gland to help protect the cable interface, a 275 would be completely immune to any of the airborne corrosives. Otherwise, go ahead and use a 204/205, it just may not last, and I doubt would qualify for limited lifetime warranty coverage when it failed (I would expect to see lots of corrosion on the board and connector). 

Thanks, that makes sense.

You can use a 204, install in a small NEMA enclosure, plumb with bulkhead connectors the ethernet and two RP-SMA cables, and you can get more or less close to the protection needed for the pool (thermal is usually an issue outdoor, but not indoors). Cost would be around an additional $300-400 all in with installation. If done right though, it will protect your AP from water splashing, when it gets hosed down, and from constant exposure to chlorine gas. 

it is a swimming pool but just bigger...

I was thinking about the outdoor AP but the cost doesnot work...