You leap from the high window. You fall, fall into the water, where you will be safe from Captain Nemo. (Please ignore the basic flaw in this plot point.)
You swim away from the tower, but no land is in sight. The Drinking Gourd is your guide, which would be fine if you were a slave escaping to Canada, but since there is no land to the north it's a fundamentally bad idea. Anyway, you lose consciousness.....
or it it?