Bear in mind that Tumaco is a port town with endemic poverty. Take extra care navigating the crowded daytime and barren night-time streets. If going out night clubbing, take a taxi home.
The road to Tumaco is yet in a zone seeing sporadic activity by armed factions of the civil war and narco-traffickers. However, with the heavy Colombian military presence, the situation has much improved. Check on safety conditions before embarking on your journey. At the time of writing, the road was okay.
The threat of tsunamis is now taken very seriously in Tumaco. If there is an earthquake, follow instructions and get to higher ground.
As the area experiences great rainfall, take precautions against malaria and dengue. Many hotels have screened windows; those in Playa El Morro also have toldillos (bed mosquito nets).
Take particular care with food and water. Treat all tap water or drink bottled water; the tap water at El Morro is only suitable for bathing, as it has mangrove particulate matter.