Maybe helpful to visualize the area of Groenendijk / De Oude Wilck / De Slingerkade, etc. are these maps made in 1610:

https://www.rijnland.net/@@archieven-proxy?mivast=319&mizig=42&miadt=319&miaet=14&micode=30A&minr=1056884&milang=nl&misort=last_mod%7Casc&mizk_alle=rijnland&miej=1700&mif2=1817&miview=viewer

https://www.rijnland.net/@@archieven-proxy?mivast=319&mizig=42&miadt=319&miaet=14&micode=30A&minr=1057100&milang=nl&misort=last_mod%7Casc&mizk_alle=rijnland&miej=1700&mif2=329651&miview=viewer

I think the Slingerka(de) was the road along the shore of the "Oude Wilck" (the Old Wilck). The name of the Oude Wilck changed to "the Slinger" as it is stil called now. Seen from the Rhine behind the Oude Wilck lies Benthuizen and on the east side of the lower part of the Oude Wilck lies "De Bent". Also visible on the east side on the map is the Dwarswetering running out of the Piswetering (which is now called the Padesche Wetering). 

Btw, as the discussion here also mentions the Ket family, on the map the name Claes Ket is mentioned on the north side of the Rhine river.

Here is another interesting map of the Delfpolder in 1597 which is situated between the earlier mentioned Dwars- and Piswetering, with an overview of how the plots where divided with the names of the - I suppose - owners (did not study the map thoroughly yet). The name Oot Adriaenssz van Slijngelant is mentioned on it (this could be Otto van Slingelant who was married to Aechte Dircksdr. They had at least 5 children, among who Adriaen Ottensz van Slingelandt married to Maritje - btw the other children where Dirck Ottensz, Annetgen Ottensz married to Aert Dircxsz Turckenburch, Machteld Ottensdr and another daughter with -for me- unknown first name who was married to Henderick Lucasz). 

Attention, the left side of the map points North so to the Rhine:

https://www.rijnland.net/@@archieven-proxy?mivast=319&mizig=42&miadt=319&miaet=14&micode=30A&minr=1055376&milang=nl&misort=last_mod%7Casc&mizk_alle=rijnland&miej=1700&mif2=329651&miview=viewer

Interesting, and especially thanks for pointing out the presence of the name 'Claes Ket' on the maps created by Floris Balthasars van Berckenrode. I've looked at those maps dozens of times, but never noticed that. It may very well refer to Claes Willemsz Ket, a person being discussed in this topic. The dates could add up I think.