One of the places to watch the Boat Race is from one of the official fan zones. There are two official spots: The Hammersmith Fan park in Furnival Gardens and the Fulham Fan Park in Bishops Park. Both zones are open from 12noon and have big screens showing the BBC coverage of the race, food stands, bars and, essentially, loos. Both are also dog friendly.
Do note: alcohol can’t be brought into the Fulham Fan Park, but is allowed in the Hammersmith Fan Park – just incase you were wondering (don’t pretend you weren’t, now).