The victim was assaulted by a group of assailants first in Skipper Way and then in Alver Valley Country Park between 7pm and 7.30pm on Friday, December 11.
The 16-year-old boy suffered injuries to his head and face, including a fractured eye socket.
Police have arrested and bailed a pair of teenagers in connection with the assault, according to a spokesman from Hampshire Constabulary.
He said: ‘A 19-year-old man from Fareham and a 17-year-old boy from Lee-on-the-Solent have been arrested on suspicion of causing grievous bodily harm.
‘The two arrestees have been bailed until January 15, 2021.’