It depends on the season. In Ushuaia during the winter, the best option is skiing and snowboarding in Cerro Castor. There's also a Winter Center, with a lot of winter activities. I have been to the Tierra del Fuego national Park by bike during the winter, but it's not the best season for that. In the summer, there are different activities, such as trekking, hiking, climbing, biking, kayaking and much more. Enjoy!

Visit perito moreno in el calafate then go to puerto natales and do the hiking in torres del paine. It is amazing. El chalten is also amazing!

Both of them are really nice, but for my surprise El calafate is more interesting then Ushuaya! At El calafate do not miss the day trip to El Chalten, where you can take the trail to see the Mount Fitz Roy!! At Usuaya go to the presidion and take part of the theatre inside it!! and do not miss the boat trip to see pinguins!! take care of your belongings all the trip

at calafate you will visit the most impresive glacier Perito moreno with a day trip(not expensive)after that you will fly to Ushuaya and will take the cruze arount the Cape horn.(1200$ per person )We did it last year and i cannot stop thinking about it..