But I wouldn't say it's a late-game thing. All you need to get them is to defeat a stack of elementals and swim there, as the groups themselves aren't guarded. Those who want a bigger challenge might choose not to take them. Oh, and I really enjoyed when, being naive, I decided to dig up the "Tear of Ashera" in the same place where it was located last time :D. And also, there are a couple of questions if you don't mind.
1. This is interesting, approximately how quickly can you complete a map (hero, veteran)?
2. How important is the "Lord of the Seas" quest for completing the game, as unfortunately, I can't complete it due to a bug (I wrote about it above, the situation repeats).