Actually, that is not the right one. It goes over to Odaiba.

The water taxi I was referring to is this one: http://www.tcvb.or.jp/en/infomation/7recom/net5.html .

It goes from Asakusa to Hinode and vice versa, but has an intermediate stop in both directions at Hama Rikyu Imperial Garden. It is also a lot cheaper than the fancy new "glass boat" to Odaiba.

JR