The longest River is Nile and Amazon. Which one exactly, remains an open question. Nile considered to have 6,695 km in length.
The highest active volcano is Ojos del Salado, at the border between Chili and Argentine. It's height is 6,887m.
The smallest continent is Australia - area 7.614 million sq. km.
The fastest iceberg, 54 km in length, 4.8 km wide and 910 meters high somewhere near Columbia. This iceberg moves with the speed 35 meters a day. You may consider this is very little, but actually it's not. Normally icebergs are either static or move at the speed of 1m/day.
The deepest valley. The Grand Canyon is big, but not as big as the valley near the river Jarpun-Tagbo, crossing Tibet and Bangladesh. It's deepness is about 5,000 meters, which is approximately 3 times deeper than the Grand Canyon's.
What else do you know about the Earth?