Answer by taking a quote from the following article:

Santana is a Latin music and rock band formed in San Francisco, California in 1966 by Mexican-American guitarist Carlos Santana. The band came to public attention with their performance of "Soul Sacrifice" at Woodstock in 1969. This exposure helped propel their first album, also named Santana, into a hit, followed in the next two years by Abraxas and Santana III. Lineup changes were common.

13 months after Caravanserai, Santana released Welcome. Welcome was the first of four consecutive albums to achieve gold certification, as opposed to the previous four, which all at least reached platinum status. The album peaked at number 25 on the Billboard 200, the lowest of the band's career so far. The next few albums contained a more experimental style than their previous work, beginning with Borboletta, which fared arguably worse than its predecessor, despite climbing five spots on the US charts.  The group's 1976 release, Amigos, was far more successful. Reaching number 10 on the US charts, and also hitting the top 10 in France, Australia, New Zealand, Austria and The Netherlands, it was a form of return to the success of their early albums. Festival, somewhat contradicted that new-found success, but was a short blip before another successful album, Moonflower, released in 1977. The album was possibly the most successful since Santana III, achieving 2x platinum in the US, and being the first album since 1974's Borboletta, to break the top 10 in the UK. It was characterized by a stylistic shift for the band, as it contained heavier influences from the more conventional sound of the group's early work, while still maintaining the experimental sound of their last few albums.  Their next two releases, Inner Secrets and Marathon, released in 1978 and '79, respectively, were a further musical shift for the band, moving away from the Latin-fused rock music that had characterized their work in the late 1960s and the majority of the '70s, to move towards a more album-oriented, conventional rock sound. These albums, however, fared poorly commercially, although both achieved gold status in the US.

What did they release next?
Moonflower, released in 1977.