Leave La Paz at around 7 am. After aproximately 3 hours you will arrive to Tiquina, the narrowest part of the lake, where you will cross to the other side by boat and meet the bus on the other side to continue with the trip, after another 30-40 minutes you will arrive to the town of Copacabana.  Once there you will have lunch and then head towards the shore to catch a boat to the Sun Island, in the south part of the Island you will see the Inca steps and the Inca fountain, also known as the youth fountain, this fountain represents the 3 pillars of the Aymara Culture, Ama Sua, Ama Llulla and Ama Quella, which mean, you shall not steal, shall not lie and shall not be lazy.  Afterwards you will visit the town of Yumani and then start heading back to the port to catch the boat back to Copacabana.  Once in Copacabana you will visit the Church, main square and crafts market and by 6 pm you will catch the bus back to La Paz, you should arrive back in the city by 10 pm.