College level courses in Spanish, online
I recently found out about miríada, a website that teaches online courses in Spanish.
Courses are offered by many participating universities, and cover a wide range of topics such as Chemistry, Computer Science, Humanities, and History.
They are offering a Spanish language class starting June 2 for folks that already have an A1 level of proficiency in Spanish. Español Salamanca A2 is offered by miríada and the Universidad de Salamanca.
If you're beyond A2, there are courses taught in Spanish with content that doesn't look like it will be too intimidating. For example, Introducción Arte Lationamericano con Énfasis Colombia.
There's also Coursera which, while primarily offering courses in English, also has courses taught in Spanish. I have taken one course from Coursera in English, and it was fantastic. I'm considering taking a course or two in Spanish with subject material related to my work. The content should be familiar to me, so I will have time to focus on the language.
You can expect videos, reading material, and quizzes. The class I took before didn't have any group work or live talking to others; it was self-study with help from a support forum of other folks also enrolled in the course, plus instructors from time to time. I've signed up for one that looks like it will involve some group work. It will be interesting to see how they accomplish that with students from all over the world in different time zones and with differing schedules.