The Dark Cloud over Sun Island
Trekking the length of Isla del Sol from the north to the south was once one of the great joys of visiting Lake Titicaca. That's no longer possible. Tourists have been restricted from traveling north of Yumani (and its satellite village of La Estancia) due to an ongoing conflict between the communities of Cha’lla, in the middle, and Cha’llapampa, to the north.
The conflict began in earnest in March 2017 when the people of Cha’lla built a hostel near the ruins of Cha’llapampa in an attempt to cash in on some of the tourism revenue that had long evaded them. This angered the people of Cha’llapampa so much that they blew up the hostel with dynamite. Thing is, the people who now live in Cha’llapampa settled the area from Cha’lla, so the whole ordeal has turned into a family feud writ large.
In retaliation for the hostel incident, the people of Cha’lla instituted a blockade on the north, preventing tourists from traveling there by land or sea. Rather bizarrely (given the cause of the conflict), tourists can't even drop by Cha’lla for a visit, though you should be able to loop around Cerro Palla Khasa.
In theory there should be someone at a guard post stopping you if you walk too far from Yumani. In practice, this doesn't always happen. Either way, do not be tempted to test your fate. A Korean tourist was stabbed and strangled under mysterious circumstances in early 2018 shortly after a heated exchange between the two communities to the north. No one was charged with the murder, but it was suspected at the time that she had unwittingly crossed into the northern half of the island.
These unfortunate events should by no means stop you from visiting Isla del Sol. Stick to Yumani or La Estancia and your trip will likely be perfectly safe and conflict-free. In fact, you may never even realize that there are troubles brewing in the north. As with any conflict, it's best to check with hotels and tour operators in the region (namely Copacabana) before you depart for Isla del Sol to find out the latest, as everything may have been resolved by the time you read this.