During summertime,the north Indian Ocean circulation is characterized by eastward Southwest Monsoon Current (SMC) which is essential to the transport of water mass in the west and east ocean basins in the tropics.Occasionally,a narrow westward coastal current (hereafter referred to South Sri Lanka Coastal Current,SSLCC),against Southwest Monsoon (SWM) and SMC,exists off the southern coast of Sri Lanka at the same time.In this study,ECCO data is used to examine the dynamics and inter-annual variations of the narrow westward coastal current.It is found that the formation of the westward SSLCC is closely related to local circulation in the Bay of Bengal (BOB).The southward moving East Sri Lanka Coastal Current (ESLCC) which is associated with the western flank of Sri Lankan Dome (SLD) turns to westward along the northern flank of Small Cyclonic Vortex (SCV).The SCV is a cold upwelling dome,originated at the south of Sri Lanka.The strong SLD is the key factor to intensify the SCV which favors the westward SSLCC.This phenomenon is observed in the years of 1993,2002,2004 and 2011.However,the ESLCC turns to eastward with the SMC during the years which have weaker SLD,such as 1994,1997,2003 and 2008.The possible reason is that the SLD is unable to intensify the SCV.The analysis suggests that the strength of SLD plays a significant role for westward SSLCC.