The minimum water depth in waters adjacent to the TSS and two-way route located in the vicinity of Halder buoy is 11.1 metres and in the traffic lane 13.0 metres. Mariners are adviced to navigate with caution and proceed at a safe speed. Vessels with a draught of more than 7.6 metres are adviced not to navigate in TSS in the vicinity of Halder buoy and in the two-way route. The main route through the South Åland Sea is the TSS and DW-route located in the vicinity of Svenska Björn Lighthouse.