Pulau Sipora is the least extensive island but it's the most populated and better communicated. Tua Pijat is a good place to start your unique experience. You can start by doing some walking or going on a boat trip, along with getting information about your accommodation. Sipora has a rich biodiversity, a high percentage of rainforest, different monkey species, lizards and unique insects. You can still see the devastating effects caused by the Tsunamis of 2004 and 2009 but you'll be surprised to see that despite these natural disasters and their constant threat, the people haven't lost their smiles.
Sipora is a remote place and the locals live in their own time and space in total isolation from the rest of the world, especially in the interior parts. You'll find friendly, self-sufficient people that are living in huts surrounded by animals and other traditional necessities. It is, without doubt, an incredible place to get to know Mentawai and embrace the local saying "Moile Moile" which is a spiritual belief to look after the soul, and means your actions should be calm, without pauses and with total dedication. Make sure you don't get stressed or nervous here because this attitude is not only considered by the Mentawais as an insult, but also a bad omen.