What doors open the Valor dive puzzle ?

[Vhein]

Hi, simple question, because none of the two doors you can found inside the dive spot seems to be opened, and if i recall correctly at the end of the puzzle it says " a door was opened somewhere ", something like that.

 

I killed the kingdra, is it where the door was ? Never payed attention.

[DanelerH]

Yes.  There was a gate blocking it.