As a resident of Nijmegen (Netherlands) I would like to add some information about the river uboats type Biber. On the website there is no mention of Biber operations from Emmerich on the river Rhine. These did occur however.
After the failure of operation Market Garden in september 1944 (A bridge too far), the Germans were keen on taking out the river bridges in Nijmegen-Arnhem area. Also the bridges over the river Waal at Nijmegen were targeted. Not only by Luftwaffe Jets (Mess. 262) and commando-opererations (divers, of which one was an Olympic swimmer). Also they used Bibers to bring down the bridges. This happened in the period october to december 1944. Although the railwaybridge was destroyed and the trafficbridge badly damaged, this German succes was thanks to the special forces divers. To my knowledge the Bibers didn´t succeed in their missions.
The best proof of their use was the finding of one stranded along the river Waal in 2009. This one made it´s way to the museum in Overloon where it on display. This fact is mentioned on the website. Though there is no reference to it´s origin.