There can be a quite strong undertow in the sea so be cautious when you swim. When I visited Pochomil in July 2010 the currents felt extra strong. I have read that Pochomil is good for surfing most of the year, but not when I visited. Three surfers staying at the same hotel as me said the currents were too strong at the moment for surfing. And one of the evenings I was there the water level got extra high and reached far up the beach and beyond the restaurants. People from Pochomil were out watching and a woman told me this was not normal, at least not at that time of the year. I think it might have to do with the weather phenomena El Niño.
That is, there is very little infraestructure here for shopping, dinning etc. BUT, that's the point. If you want to get away from the thronging crowds, here's a great place to do it. Taxi's are cheap and a bit rough in condition yet, reliable. Additionally, it is very common that the driver will pick up other passengers if there is room in your taxi. Don't freak out about it. There's no danger here of violence. I wouldn't allow this in Managua however or Mexico City, Paris or even Los Angeles.
The wave patterns here are relentless...don't drift far out unless you are a very capable swimmer. They aren't that big; its just that they keep coming at a much quicker rate then many are used to. Waves here are good for beginning surfers.
There is always a danger when swimming on the beach. Know your own strength, Dont go out alone , try to stay in the site of the people you are with. There is strong current that moves north on this beach. And some of the wave my surprise you (that goes for every beach) so be aware. Take breaks and never swim if you feel too tired. I dont know how to swim so I never went far out... And i dont recall seeing a life guard but I'll ask if anyone in my group did. But I got wet and had a good time. Use common sense and Enjoy yourself.