a teen boy who helps a ghost w/ his unfinished business (drama)

it’s a 2015(?) movie where a teenage boy tries to help the ghost of a teenage boy(who committed suicide by drowning) with his list of unfinished business. the ghost’s unfinished business turns out to be revenge.
in the final scene the teenage boy takes the ghost to a tunnel to deliver him to the afterlife.
notes:
I remember that the ghost led the boy to where they found his body. the boy sleeps there then his brother and his friend find him. also, the ghost was obnoxious, thin and (wearing glasses?).