Thanks for the report Sniffledoo. Yes, the coin is for
another quest, but the underwater part of your report is interesting. I
used the underwater breathing spell and searched the deep water area below
the water wheel looking all over for a secret part of the wall, but found
nothing. I think now I'll try the rest of the Ak'Anon underwater areas
unless someone else has already done so. Long ago I heard someone shout in
Steamfont that the 3rd book was in Akanon somewhere, but that was before I
got interested in Tinkering (probably before I even knew what Tinkering
was), so I have no idea how true that information is.

As far as other underwater areas to explore where the 3rd
book might be located that I know of are: 1) Kedge Keep in the Cauldron zone
(but I hear that zone is not itemized yet until next patch), 2) under lake
Rathetear there is an area of high level Gobs and 3) in Everfrost there is a
small underwater area with an NPC who usually attacks anyone on sight. I
have not searched any of these areas yet. Anyone know of other underwater
areas?

Good luck brothers and sisters!

Kilkin Cobblepot - 25th Gemchopper - Fen Ro
Kilzixplik - 18th Enchanter - Fen Ro