Danger Island COMPLETE mini-series
https://en.wikipedia.org/wiki/Danger_Island_(TV_series)
Danger Island is a live-action adventure serial produced by Hanna-Barbera and originally broadcast in 1968-69 as a segment of The Banana Splits Adventure Hour.
Danger Island depicted the adventures of a trio of explorers in an unnamed tropical island group: Prof. Irwin Hayden, an archaeologist; Lincoln "Link" Simmons, the professor’s youthful assistant; and Leslie, the professor’s daughter, who serves as both a love interest for Link and the series’ token damsel in distress.
Several years earlier, the professor’s brother (also an archaeologist) disappeared in the same island chain while searching for the mythical lost city of Tobanya…
https://www.kprotector.com/p18/62385385a7ec4