The astronomical tide range in Pusan Harbor is relatively small, ranging from a spring rise of 4 ft (1.2 m) and neap rise of 3 ft (0.9 m).

In the area of the Korean Strait about 10 nmi off Pusan, the surface current flows in a general northeast direction at a velocity which is constantly changing but usually somewhat exceeds 1 kt. The combined flow of the current and tidal currents reaches its maximum velocity about three hours after the time of high water at Pusan, and its weakest about three hours after low water. A southwest set may be experienced when the ocean current is weak.

In the vicinity of Saeng Do, about 0.75 nmi south of the south end of Yongdo (Yeongdo), the tidal currents are very strong. The flood current attains its maximum velocity east of Sangi Mal (37°00.145'N 126°44'E), and the ebb current between Saeng Do and Yongdo. The tidal currents have a velocity of 2.5 kt in this vicinity and there are often overfalls during the ebb current. An overfall is defined as a turbulent surface of water, caused by strong currents setting over submerged ridges.

At the approach to the entrance of Pusan Hang the tidal currents usually set southwest with the rising tide, and northeast with the falling tide. Within the Harbor, the maximum velocity of the tidal currents is about 2 kt, and it sets in the same directions as the approach.

In the approach to the south entrance of Pusan Hang the tidal currents set in a northerly direction with the rising tide, passing around the northwest end of Yongdo. Here the current unites with the flood currently flowing in a southwest direction from the north entrance. Together they flow in a west and south direction along the mainland and out to the open sea. A part of the north current strikes the southwest coast of Yongdo and is deflected east and south. Then it joins the main current setting south along the mainland to the open sea.

In the North Inner Harbor, the tidal currents set southwest through Pusan Hang, with the rising tide, and northeast with the falling tide. The maximum rate is 2.3 kt. Strong currents at their maximum rate are reported to set through the entrance between the breakwaters separating the North Inner and Outer Harbors.

The pilots stated during the Site Visit in May 2009 that strong tidal currents exist across the Main Channel at the entrance to the Outer Breakwater in the North Outer Harbor which may hinder a safe approach to mariners inexperienced with the Port.

Source: http://www.nrlmry.navy.mil/port_studies/thh-nc/korea/pusan/text/tides_and_currents.htm