You can take a bus or take a leisurely stroll about 10km West along the beach to the small Garifuna village of Santa Fe. The town has an attractive beach front and the water is significantly cleaner than the beaches of Trujillo.
Hungry? The Caballeros Restaurant is not only one of the best restaurants in Santa Fe; it's one of the best restaurants in Santa Fe AND Trujillo. The fare is the usual stuff - chicken, meat, fish - but the portions are huge and the chef uses a sauce that tastes so good it is to die for.
Don't bother asking him; he won't give you the recipe.