boat transportation on the coast

I've searched online for an answer, but to no avail. Is it possible to take a boat from Machala to Posorja or Playas? We're in Vilcabamba now. We want to take a bus from Loja to Machala and then get to Playas without having to go north to Guayaquil and then another bus from there. It looks like we could get a boat to Isla Puná from the port near Machala and then maybe a boat from the north of the island to Posorja, but I'm not sure if that's possible. I think the island would be interesting and we've been riding buses for five months so a boat trip sounds more appealing right now! Thanks!