Unless you are checking every single corner you come across in Prince of Persia: The Lost Crown, there is a real chance you will accidentally miss finding Fariba. She shows up in every section of the map, and giving her 50 time shards will reveal all corridors in that area. Having a layout of the area is incredibly useful for finding secrets and other oddities. With that in mind, here is the Fariba location in Sunken Harbor in Prince of Persia: The Lost Crown.
Where to find Fariba in Sunken Harbor in Prince of Persia: The Lost Crown
The Fariba location in Sunken Harbor in Prince of Persia: The Lost Crown is located south of the Pirate Village fast travel point. If you are returning to this area to find her, head west from the statue and then drop down into a room filled with hanging platforms, flying enemies, and some mines. Take your time and navigate your way through here without landing on the spikes at the bottom.
When you are here, make your way to the west side of the room and climb until you find an elevator. Use your chakram by holding your bow button and throw it into the pulley above it to lift yourself to where Fariba is sitting. The screenshot below shows the spot.

Just like every other time you find Fariba, it will cost you a mere 50 time shards to reveal the area on your map here. It is highly advisable you do this before you go searching for collectibles and secrets in the area. Having a good idea of how the rooms sit around you can help you plan your route much better.