We do it from Peru side.
You have to go to Puno port and buy one of the excursions they sell that could be just for a lake trip or you can stay one night with a family in Taquile or Amantani islands.
That option is very recommendable.
You also have the option to talk with a fisherman and negotiate a better price, but my advice is to buy a tourist excursion, because it's not expensive and nobody there speaks English so you may end up visiting a beach or going to Bolivia because of a misspelling.
"Can I see anything special?
" You will see how these people live every day without electricity and some other comforts of modern life.
travel.stackexchange.com/users/1425/Ivan
Besides the trips from Puno the other popular boat ride on Lake Titicaca is to go to Isla Del Sol , an island on the Bolivian side.
You can either do a day trip from the Bolivian town of Copacabana close to the Peruvian border, or stay on the island in one of the numerous basic guest houses.
You can easily spend a day walking around the island and go swimming.
There are some Inca ruins as well
but I did not find them very impressive.
Photo credit Peter Hahndorf
The boat ride itself is about an hour from what I remember, and it does help if you have a sunny day when visiting the "Island of the Sun"
travel.stackexchange.com/users/1317/Peter Hahndorf
Very possible.
Last year, with a friend, we bussed from La Paz, Bolivia in the early morning to Puno , Peru, on the west side of the lake.
By mid afternoon we'd checked into our hostel and booked and were on a trip to the Uro Islands on the lake .
We had a storm on the lake as we were leaving the islands, which added to the dramatic landscape and scenery.
For a description of the tour and my trip, I did a write-up on a blog page .
I should point out that once on the islands, I've never felt like I was in such a tourist trap as much as that moment.
They're very cool, and worth seeing, but you really felt like you were
(And you literally were!)
trapped on an island with pushy sellers.
travel.stackexchange.com/users/101/Mark Mayo
I did a 2 days boat tour with a home stay on Lago Titicaca this February.
The boat leaves Puno at around 9am and we arrive at Taquille Island about 2.5 hours later.
Taquille Island looks like a very peaceful paradise where the community leads a very simple life.
The altitude will start weighing on you as you climb towards the middle of the island if you haven't been acclimatised yet.
We had lunch on the island and it was delicious.
They plant quinoa locally there and we had quinoa soup as a starter followed by fresh fish from the lake.
Around 2 pm or so, we started to climb down to the other side of the island where our boat was waiting for us.
Another hour of boat ride
and we reach the peninsula where we have our homestay.
I got to live and experience living as the local people in this region as well as embracing their culture.
There was a dance at night and you will have dinner with your homestay family.
I recommend you bring a Spanish dictionary or at least learn some Spanish words.
Given my limited to non existent Spanish, I was forced to communicate with the homestay family by flaying my arms around and pointing at things around me.
On Day 2, we say goodbye to the family and leaves at 8am to Uros, the floating islands.
That took around 3 hours by boat.
The floating islands made of reeds looks out of this world, it's quite a sight to behold.
After landing on one of the man made island, a local will give you the history and how it was built.
After that, it's another hour by boat to Puno, we also had lunch on the boat.
We were back in town by 12:30 to 13:00.
Visting and living on the island is probably the best and most rewarding experience if you are visiting Puno and Lake Titicaca.
travel.stackexchange.com/users/78/Thierry Lam
I am visiting Lake Titicaca next week and will be taking a tour offered by All Ways Travel .
I chose them based on the recommendations from my friends who have taken Lake Titicaca tours with them.
Lonely planet and other travel guide books also recommended them.
Again, I am yet to go there
so take my advice with a pinch of salt!
travel.stackexchange.com/users/1538/tntb4u
Is it possible to do a boat tour on  Lake Titicaca ? Where should I start? And are there roundtrips possible? Is it recommened to do a boat tour there as a tourist? aAnd can I see anything special?
Boat tour on lake Titicaca?
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<tours><sea-travel><bolivia>
travel.stackexchange.com/questions/4227
travel.stackexchange.com/users/693/RoflcoptrException
It is very possible to do this from Puno in Peru or Copacabana in Bolivia, close to the Peruvian border. Excursions could be just for a lake trip or you can stay one night with a family in Taquile or Amantani islands (Peru) or Isla del Sol (Bolivia). Visiting the islands is a rewarding experience where you can see how these people live every day without electricity and some other comforts of modern life.  Boat trips on Lake Titicaca are available from Peru and Bolivia. The highlight of the trip is seeing the way of life of the local people.
There are two main points for departing on a boat trip on Lake Titicaca: Puno in Peru or Copacabana in Bolivia. The main interest of the trip is seeing the way of life of the people living there.