Size:  

The largest one seen so far measued just over 32 feet (10 metres) in length.

Age:

Their lifespan is not yet known

Feeding:

This kind of shark eats plankton (aka Krill). It has a  filter which allows seawater to pass  through the gills and out the other side while trapping the krill inside. Basking sharks have to swim almost constantly through the water with mouths wide open to collect up enough food.

Where they live:

They enjoy cool waters worldwide, and are as at home by the shore  as they are in open waters off the coast of China, Korea and around Japan, on the East coast of the U.S., from Newfoundland down to Florida, around Great Britain and Norway, but also in the Mediterranean, South Australia, parts of South America and the tip of South Africa.

Some interesting things I've learned :

Basking sharks are harmless.

 Years ago these animals were hunted for food and harvested for oil. They are now on the  list of endangered shark species.

Because of their unusual appearance, Basking sharks were often mistaken for sea monsters (serpents) They love to swim directly underneath the surface of the water and "bask" in the sun.They often swim in packs  and can sometimes be spotted  "basking" in a row with their dorsal fins etc... sticking up out of the water.