A sustainable small hotel (18 rooms) on the sea front, this hotel benefits from being far enough away from the city centre to avoid any hubbub and busy-ness, while being no more than a short (15-25 minute) walk away from the main square and most of the restaurants.
The waves will (if that's your thing) both soothe you to sleep and wake you up, and the sea birds - gulls and pelicans, plus the odd vulture - will help you get out of bed in the morning.
All rooms have a sea view; the hotel itself has a small, somewhat gravelly beach section, but you're only a few minutes walk from a couple of official, sandier beaches.
The sustainable side of things mostly comes in the form of recommendations - limit how much water you use (Arica is one of, if not THE, driest city in the world); put your toilet paper in the bin, rather than the toilet - but these aren't hard to abide by. Your room gets a daily jug of potable water.
The relaxed vibe of the hotel matches how the town itself has a remarkably laid-back feel, so you could probably spend as many days as you wanted to here. Alongside everything else, English is spoken widely by the staff, so it's refreshingly simple to make your needs known.