"Dredging up the past 1/3"

A very long time ago, there was a civilization under the ocean known as Ekryll, made up entirely of... Air breathers! They had little need for anywhere to breathe but the surface, and what little is known about them includes why that was the case: Even the weakest among them could hold their breath for several days at a time! For an unknown reason though, none of them are around any more, and the undersea towns they'd made are now inhabited only by fish... But their legacy remains more than that.

This lizard found out one day that he was a distant descendant of one of those aquatic air breathers! That certainly explained some things, namely an incredible breath holding ability that ran in his family; his own record was just past an hour. With that knowledge, he set out to learn what he could about his ancestors, and actually managed to come across a previously undiscovered town they'd left behind.

20 minutes into his exploration, in a section he imagined once looked particularly impressive, he opened up what sort of looked like a chest to have a look inside. There wasn't a whole lot in it... Aside from a map! The lizard sat nearby as he looked it over. It seemed to have held up well, as it still managed to get its point across despite its age. Not only that, it showed a place he actually recognized... Along with some more details, written in the civilization's language that he'd thankfully studied. A mention of the depth he'd have to swim to - just over a mile underwater! - and a warning that only one of Ekryll blood can open the way. The latter was probably sorted, assuming just a tiny bit of relation would be enough, but he'd have to go deeper than ever before... He started mentally preparing himself for the training he'd be doing to get himself ready.