so > such a
5 That like a little lake it seemed to be; 6 Whose depth exceeded not three cubits' height,
three cubits > (Four-and-a-half to five-and-a-half feet (about 1.4 to 1.7 metres); the cubit is an ancient measure based on the length of the forearm, about 18-22 inches)
7 That through the waves one might the bottom see,
That > [So that]
8 All paved beneath with jasper shining bright,
jasper > (Used to describe various precious stones, esp. of a bright green colour)
9 That seemed the fountain in that sea did sail upright.
That > [So that it] sail > sail; sally forth, issue forth, project
212.63