Is there internet/WiFi on the islands?

It varies.

• Mabul and Kapalai: Generally have decent 4G coverage (Celcom and Digi) and resort WiFi, though it can be slow.
• Remote islands (such as Si Amil, Tabawan, and Pandanan): Signal is often weak or non-existent. Enjoy the digital detox.
• Semporna Town: Full 4G and 5G coverage.