About delta location

[DOOOODGE]

Playing the story mode so far, I reached the airport and found the new map. In this map, I see a "delta" marked location just south of the anaconda camp.
By going there, I've found a water pool with a waterfall. Diving in the pool I get a "new location" mark but I can't go further because the hole is too small to pass. Do I have to go back there after getting some sort of scuba kit or that location serves no purpose?

Also, I've read in other threads that the true "delta" spot can be accessible by climbing up at 33W 33S, but I can't really go any souther than 29S from the anaconda camp area, unless I go back a long way. Should I do it or is delta meant to be reached further into the story (if so I should just skip it and go to C-)?

Also, did I miss something? Played this game in the 0.5 patch and I'm sure there was a plane crash site somewhere.

[Andrewbh2003]

1- the area your going to is acessible from another location later in the story

2- you can go to 33 its just not acessible now again continue the story and it will be revealed

3- yes plane crash is still there you probably missed it go back and find it its in the exact same location it was a year ago

[miamew3]

You need to carry on forward past the airport to the wetlands. Go to the end of the runway by the cliff and walk along it heading south-east

You will reach delta further in to the story. I will warn you delta can be easily missed, i didn't find it till after finishing the story and reloaded to the last save to carry on playing without doing the ending this time.

Plane crash is on the 1st map

[DOOOODGE]

Thank you all for the answers. I backtraked and found the plane crash site, and I also found the destroyed bamboo bridge that, in the story mode, isn't rebuildable (also a couple of caves and camps here and there).

I have another question: I'm past the third ritual site and found the third map. I also found the grappling hook gun, and decided to backtrack to the anaconda camp, because north of it I found a point where it was required.
Been there, used the gun, but there's nothing up above, just a refuge building (that I already had unlocked) and a fire lighting tool. Is it really an empty terrace? Nothing up there?

Also, I have found delta camp. It's a small camp, kinda a smalle version of the anaconda one. However, in the map I see a fireplace mark next to delta camp, at 31 29. Since My only way from delta is either back towards omega or down the hill towards the anaconda camp, how can I reach that fireplace mark?