Complex sentence: Because it is shallow, it is warmer than the deeper Finger Lakes in summer, and freezes solidly in winter, it is relatively safe and popular for the winter sports of ice fishing and snowmobiling.
Split into simpler sentences: Because it is shallow, it is warmer than the deeper Finger Lakes in summer, and freezes solidly in winter. It is relatively safe and popular for the winter sports of ice fishing and snowmobiling.