A dives is able to cut through water in a swimming pool. which property of matter does this observation show? ...

The intensive physical property of being malleable (as in reshaped by the diver cutting through the liquid matter)

First of all water gives space to everything added do it and changes its shape being malleable according to it except some cases.

Also water has fluidity it is present in form of sheets that can easily slide over each other and thus can be easily replaced ...

In this case dive is able to cut it due to these reasons ...