Complex sentence: The lake was named after Queen Victoria by the explorer John Hanning Speke, who was the first European to discover it, and which he did alone in 1858 while on an expedition with Richard Francis Burton to locate the source of the Nile River.
Split into simpler sentences: The lake was named after Queen Victoria by the explorer John Hanning Speke, who was the first European to discover it. Speke accomplished this in 1858, while on an expedition with Richard Francis Burton to locate the source of the Nile River.