S1:	We now know that the oceans are very deep.
P :	For example, the Indian ocean has a range called the Indian Ridge.
Q :	Much of it is fairly flat.
R :	However, there are great mountain ranges as well.
S :	On average the bottom is 2.5 miles to 3.5 miles down
S6:	This reaches from the India to the Antarctic.

The Proper sequence should be: