Walk as far north as you can along the beach front promenade behind Las Canteras. It goes past the big Cesar Manrique wind sculpture at La Puntilla and along the rocky shore in front of the La Isleta barrio. At the end there is a dirt track that carries on to El Confital. The first bit is shared with cars (there aren't many) and then a track with iron steps forks left. Follow this to go straight to the board walk. If you are driving then head into the maze of streets in La Isleta and aim north. You'll get lost and need to ask for directions. Thanks to Gran Canaria info website.