Second avatar of Vishnu happened during the churning of
ocean or Samudra Manthan. This incarnation was to help Devas and Asuras in
balancing the churning chord. As per Hindu scriptures the second Avatar of
Hindu God Vishnu is the Kurma Avatar – which is referred as the turtle
incarnation. The story of Kurma avatar is one that symbolically narrates the
process of evolution.
Information about the Kurma Avatar is mainly found in the
Bhagavad Purana (Canto 8 Chapter 7), Agni Purana and Ramayana (Balakanda
Chapter).
Other resources
Story of the Kurma Avatar of Lord Vishnu
Kurma JayantiStory of the Kurma Avatar of Lord Vishnu