Complex sentence: It was not until three centuries later, in 1830, that another major expedition sailed through the fjords and channels of Última Esperanza: the British expedition of the sloop HMS "Beagle".
Split into simpler sentences: It was not until three centuries later, in 1830, that another major expedition sailed through the fjords and channels of Última Esperanza. This was the British expedition of the sloop HMS "Beagle".