Why do scuba divers were a special suit while they go into deep sea levels?

Why do astronauts have to wear protective suits when they are on the surface of moon?

Why do underwater divers wearfin like flippers on their feet ?

Why do tyres have a better griop of the road while going on a level road than while going on an incline?

Two Navy helicopters A and B are flying over the bay of Bengal at same altitude from the sea level to search a missing boat. Pilots of both the helicopters sight the boat the same time while they are part 10 km from each other. If the distance of the boat from A is 6 km and if the line segment AB subtends 60^(@) at the boat, find the distance of the boat from B.