Elden Ring Ainsel River Guide: Bosses, Treasures, Ranni's Quest

gamespot.com:

Ainsel River is one of the optional underground zones in Elden Ring. It’s located beneath Liurnia of the Lakes in the upper west section of the world map, and as such, it can be accessed from the Ainsel River Well in that zone. The Ainsel River Well is only one of the locations from which you’ll be able to access the Ainsel River, but the way this zone is set up can be confusing. It’s split into a south side and a north side, neither of which connect directly unless you leap from the north to the south side in the Uhl Palace Ruins, above where the Hermit Merchant is located.

There are a few important sections to understand, including the Nokstella, Eternal City subregion and its tie to Ranni’s questline, which is necessary to unlock Ranni’s secret ending. You’ll need to enter the north side of the map by finding the Fingerslayer Blade and progressing Ranni’s quest up until you gain access to Renna’s Rise, which contains the Waygate that teleports you to the Ainsel River Main site of grace. Both sides of the zone contain valuable treasure and there is only one merchant located on the south side of the zone.

Taking the Ainsel River Well elevator down to Ainsel River drops you off near a site of grace called Ainsel River Well Depths. From here, you’ll want to enter the cavern filled with giant ants and hang a left until you reach the Ainsel River Sluice Gate. Once you reach the room with the sluice, hang right up the side ramp and onto the rampart. The site of grace is on the opposite end of the walkway. Most of the ants you face can be taken down with slash attacks and magic, but the armored ants can quickly rush you if you aren’t paying attention; your best bet is to take them out one-by-one with magic or ranged attacks