how to get from Muroran port to Lake Toyako

Hi, we are taking a cruise on Sept 1, 2014, stops at Muroran from 7am to 18:00. We would like to go to lake Toyako, onsen and ropeway for a day trip, would you please advise best transporation? bus, train, taxi, walk? thanks very much

I recommend to rent a car. Several companies have outlets around Muroran. Not only will you be able to drive to Lake Toya quickly, but it will let you efficiently explore the area around the lake which would be very time-consuming by public transportation:
http://www.japan-guide.com/e/e2024.html

Alternatively, there are buses between the port and Toyako Onsen:
http://donanbus.co.jp/kougai/wp-content/uploads/sites/4/2013/11/%E9%83...

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