[ Ferry Travel in Japan ] Ferry Yokuni from Ishigaki Island to Yonaguni Island

Yonaguni Island in Okinawa Prefecture is located at the westernmost tip of Japan and is truly a border island. This is my second time going to this farthest island, Yonaguni Island, but this time I went by ferry, which took 4 hours each way, instead of by plane! What was the journey like on the ``Ferry Yokuni'', which was once called a vomit ship?