Spacecraft traveling to jupiter from earth would most likely have to navigate through or around which natural obstacle?

Spacecraft from Earth to Jupiter should navigate through or around asteroid belt.

The location of asteroid belt is between the orbits of planets Jupiter and Mars and it consists of asteroids. Asteroids have different sizes; there are as small as half a mile asteroids and while some are the same size as quarter of a moon big.  

A lot of spacecraft have safely navigated the asteroids belt to reach to Jupiter and outer solar system though it was postulated to be dangerous. The first spacecraft to safely navigate the asteroid belt occurred in 1972 and 11 more have also safely passed the asteroid belt without any danger.