Sandra and Michael married in January 1988 and relocated from Munich to the Spanish island Ibiza to work on what would be Sandra's third studio album.
Into a Secret Land moved from electro-pop to more sophisticated areas of pop, what was showcased by the first single, 'Heaven Can Wait', a top 20 European hit. Second single, 'Secret Land', met with even greater success and is now considered one of Sandra's biggest hits while 'We'll Be Together', released as the third single to a big success, was the first song co-written by Sandra. In order to promote Sandra's music in th English-speaking world, another compilation was released at the end of 1988, Everlasting Love. The album failed to enter charts, but included a PWL remix of the title track which charted at number 45 in the UK. 1989 saw the release of the final single from Into a Secret Land, 'Around My Heart', which became another chart hit, while at that point the album itself was her best-selling offering. With animal rights and nature conservation high on her personal agenda, Sandra took part in recording a song 'Yes We Can' together with 15 other musicians as a part of the project Artists United for Nature.
ġ999 saw the release of My Favourites, a double disc album featuring remixes of Sandra's older songs and some of her favourite ballads. It was a success, charting within the top 20 in some European countries.
