Medium Transport; High Wing; 2 Turboprop Eng
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Situational Awareness; Confusion
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
General None Reported / Taken
Chart Or Publication; Human Factors
After arriving in SEA; we were assigned Gate X. Both myself and the Captain were unfamiliar with Gate X and it appeared to be blocked by another aircraft. We ended up turning south instead of east and were immediately informed of our mistake by south ramp. While this was happening; Operations informed us of a spot change. When then proceeded south on Taxiway Whiskey and parked without further incident.More detailed diagrams of Gate X in the airport information charts; and descriptions of where to look for ground personnel for guidance into a spot would have eliminated our confusion. While we had the Jeppesen plate up it was still unclear as to where we should go.
Air Carrier First Officer reported a ramp incursion at SEA airport.  First Officer stated more detail is needed in the airport charts.