Lake Titicaca is this gorgeous sapphire blue lake that borders on both Peru & Bolivia & is easily the largest high-altitude body of water in the world. It’s also very sacred Incan land as they believe the sun & the moon were created on Isla Del Sol. Copacabana is the Bolivian town on Lake Titicaca closest to Isla Del Sol & the best spot to explore the lake on the Bolivian side. In general I’d heard the Bolivian side was more charming & less touristy & I specifically read Copacabana was much more alluring with better ambience than its Peruvian counterpart, Puno. So we cruised right through Puno on the way to the Peru-Bolivia land border crossing to access Copacabana & Isla Del Sol, which was certainly the highlight of the Lake Titicaca trip. 
As a quick aside… I was a tad nervous hitting the border crossing. If you heed the US State Department’s advice, you MUST have a visa prior to entering Bolivia. I looked into this prior to the trip but it was going to take 2 months & that was time I didn’t have (yes, I’m still a procrastinator). So I did some online research to find that before the rule changed (US citizens apparently used to be able to get visas upon arrival to Bolivia but that changed in 2015), plenty of folks got in just fine. For the life of me, I couldn’t find a single example of someone who successfully crossed after the rule change. So we were rolling the dice a bit. But I wasn’t that worried as I was convinced all they cared about was us paying the $160 visa fee which is a reciprocal fee to what the US charges Bolivian citizens to visit (no one else needs a visa, only Americans bc our government makes it really difficult for foreigners to visit so some countries choose to do the same to US tourists; can’t blame them really). I was (fairly) certain they wouldn’t turn away tourists who not only want to visit their country & spend money but also are willing to pay a hefty sum to enter. So turns out I was right. We gave them some of the documents “required”, didn’t provide them with others (proof of exiting country, hotel res) but they didn’t seem to give a shit. They cared most about closely inspecting those US bills in exchange for a 10yr visa (woot woot!). Thankfully so bc that really would’ve sucked to be rejected at the Bolivian border… or just another adventure.