When Lost Sectors were first announced, I was really excited that Destiny 2 would have more exploration aspects to it. However, I can't help but be slightly disappointed that these Lost Sectors are already marked on your Destination Map from the start. Granted, they don't specifically show the entrances to these areas, but they are usually within a few paces of the icon on the map, which is unfortunate as I think it would have been more fun to discover these on my own. As you complete the Lost Sectors, the icons gray out on the map to show you've already done them. It's unknown at this time if they come back on a weekly basis, or if once they're done, they're done.
Also marked on the Destination Map are special regional treasure chests. These icons will show the approximate location of where to find hidden treasure chests. This reminds me slightly of the Golden Chests in the original Destiny, except now the game shows you pretty much where they are. Again, I'm not entirely sure why this had to be so blatantly telegraphed to the player, as it certainly takes some of the fun out of discovering these on your own.