You can find all of the theses of the new higher education community through TuniLib. Most of the latest theses are available openly online. Links for them can be found through TuniLib. Check the availability and location information of older theses also in TuniLib.
In TuniLib you can limit the search to thesis. If you select dissertations you'll also find printed dissertations of other universities that are in the library's collection. Only the meta information of the thesis is searched.
Openly accessible theses can be searched also directly through the repositories. In Trepo and Theseus the full text of the thesis is searched. You can also browse the theses there by faculty/degree programme/study subject.
You'll get the most comprehensive result by searching both in TuniLib as well as directly in the depositories.
Those newest theses of the University (beginning 2019) that are not available openly online, you can only read on theses access points at the Hervanta, Linna and Arvo libraries' premises.
Thesis from other universities in e-electronic form can be found in each university's own institutional repository.
Most of the thesis can also be found through the national Finna search portal. Printed versions of theses can be searched in the respective univeristy library's own catalogue.