Lol, I got a lousy Elven Helmet (Khajiit don't where head gear) and 86 Septums lol.
Anyway, the Grotto was the Black Bloods base Camp where they would dock their boats until an ambush. However (listening to the patroling bandits) A cave-in happened trapping their ships and crippling the Black Bloods ability to do Sea based attacks until they made a "Big Score" to buy more ships. That "score" was the basis of that quest line.
Ah-ha- thanks for the info! I was too busy faffing about when I entered the cave, and I didn't listen to the bandits talking at the start. Now I know!
Oh yeah... and so loot is levelled and particular to what kind of character you are?!