Second time so far in this life of mine.  
First?  Best friend's wedding ring lost in a lake.  He didn't mean to lose the ring; it just happened.
One very stormy week later we returned to the scene of the crime, as his wife insisted, and I found the ring.  We'd brought scuba gear up to this lake in Northern California, Klamath country--just in case--but simple free diving resulted in recovery.  (Mucky bottom with a fine layer of moss-like webbing above two feet or so of mud; ring caught in that webbing: lucky.)  My first real lesson in comparative geography: the lake was a mere 17 or 18 feet at the deepest, which fit the surrounding environment of rolling hills, glades, and gentle valleys.  (We were a steep hike up from the Klamath River, but on that plateau the shifts in elevation were mild.)
Night-diving the shallow lake with that scuba gear and watching plump, pale-bellied frogs sleep beneath the lily pads: that was the real high of the trip.  I still like how my buddy's wedding band appeared to me when the swirling cloud of disturbed muck finally settled, me holding my breath as long as I was able, not straining, but anxious for success, and the gold ring shining even at depth.  (Gollum, gollum.)  Those frogs, though, sleeping and dreaming.  I have a fondness for frogs.
Finding the lost truck keys in the Klamath River was a harder task by far.  Different trip.  Not my keys, by the way, but my ride back to camp four or five uphill miles away.  Of course, I had the goggles, and so I had the glory of searching and of finding.  The Klamath is a fierce, cold river; fortunately, the keys had fallen out of a pocket in the eddying pool where we'd spent most of our time.
Nisus of Troy.  Maybe I need a fourth tattoo.