Around 140.000 triangles/frame (not all are visible of course).
Edit: triangle count is only one part of the equation, the other one is object count. The test renders the water and the terrain in large chunks, but each tree is an individual object. The test has 500 trees visible (out of 3000 for the whole terrain) at a time at max. Has anybody noticed some tree popping, i.e. trees that are there in one frame but disappear in the other? That might happen if the number of visible trees exceeds the tree pool size of 500...but i can't try this for myself as my frame rate is so low.