Is the red sea a divergent boundary?

Yes. The Red Sea is actually a geological phenomenon in that sense. It gives geologists a chance to study what happens when two continental plates separate. The actual name for this process is called continental rifting. As the two continents move apart, an elongated depression forms. Eventually, this depression fills with water, which over time, creates an ocean. The Red Sea is part of the East African Rift, and is currently in the early ocean stages.