Surface Tension
The weight of the needle is pulling the surface downward; at the same time, the surface tension is pulling it up, suspending it on the surface of the water and keeping it from sinking. Notice the indentation in the water around the needle.
Source
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"OpenStax College, Water. October 16, 2013."
http://cnx.org/content/m44392/latest/Figure_02_02_04.jpg
OpenStax CNX
CC BY 3.0.
