Just to add some info on the Desolace chests...
I went to the Desolace chest area at LP lvl 156 and they conned orange to me so I'm assuming they are first LPable at 150 (155 at the max). I got all the way from 156 to 225 very quickly (30min or so). The chests turn green at 200 but still give good skill-ups up until 225. At 225 they still con green, but I wasnt able to get a single skill-up off of one.
The majority of the chests are located around the underwater naga-infested ruins between the two lil islands that appear on the map. The exact position of the ruins is (37,21). There are a few chests in the ruins themselves but the majority of chests can be found all around in the surrounding areas (all are found in easy to see sandy areas, none in the jagged rocks). There are so many in fact that as soon as you're done LPing one section more in another section have spawned.
The following is a lost of locations where waterlogged footlockers appear:
33,24
33,26
34,20 (x2)
34,21
34,25
35,19
35,20
35,23
35,24
36,20
36,22
36,25
37,22
37,23
38,19
38,20
38,22
40,18
40,20
If you're hellbent on getting all the chests in the area go ahead and use the precise locations, but I think generally it's easy enough to find em just by swimming around. The footlockers go all the way down the coast line until the wrecked ship where I found one chest, but nothing more beyond that.
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Also, a lil side-note for the chest in the lone house at the Venture Co Mine in STV: I went there at LP lvl 130 and wasnt able to open it. I returned at 156 and still was unable to open it. Someone had posted before that it conned green to them at 161 so I dunno what's up. Maybe Blizz has upped its skill level recently. /shrug