The sled symbolizes the memories that carry Jonas from the community where he grew up to Elsewhere.
The river is a symbol of the uncontrollable. It flows away from the community and is out of the control of the community.
The depth of vision that Jonas possesses is an ability to understand what he sees.
The light eye color of Jonas and the Giver connects the two characters in what feels like a genetic link. The similarity of their eye color makes them seem to be connected.
To Jonas nakedness stands for freedom. And it stands for peoples' ability to really know each other.