[TXnMA]

"That said, from what I know of the straits a meeting situation is not common. Because of the currents traffic is generally one-way through the straits-stemming the current. Down stream traffic is discouraged and maybe even prohibited, I can't remember for sure. "

Wakes visible on satellite images of the area indicate lots of traffic -- going in both directions simultaneously.

[GATOR NAVY]

I went back and checked the Sailing Directions and sailing against an adverse current is a recommendation, not a regulation so there will be two-way traffic. I'm willing to bet a lot of the traffic going against the current is smaller.

A vessel should, if possible, avoid transiting the strait or entering or departing harbors on either side of the strait with a following tidal current, but if this is unavoidable vessels should not do so when the tidal current is running at full strength.

It is not safe for large vessels to transit the strait with any appreciable following current, or at SW when numerous local craft encumber the fairways.

Large vessels with sufficient power should pass through Hayatomo Seto with an adverse current of more than 2 knots and less than 4 knots; about 3.5 knots is reported to be advantageous, as by this time the possibility of meeting any ocean-going vessels proceeding in the opposite direction will be at a minimum. When a current exceeding 4 knots is running, the strait should not be attempted as strong eddies may cause a dangerous shear.

Sailing Direction Pub 159 Japan Vol II