Lorient is a large city in the Brittany area of France. It's main industries are ocean-related (huge fisheries, and sail racing world class micro businesses). The city was almost completely destroyed during World War II, and so lacks some of the charm you can find in other similar size towns in Brittany such as Vannes or Quimper but it is definitely worth a visit, especially for history buffs.
The remains of the German occupation are still present in the harbour area where you can see massive concrete warehouses used to build and shelter submarines. There have been attempts to rehabilitate the city and upgrade its image with a sail racing museum and other attractions.
Of course, the main attraction for visitors to Lorient is the huge (largest in the world) Celtic festival which happens every year at the beginning of August. The festival draws massive crowds to the various concerts and shows. There are plenty of free events during this festival, including the main event, the Sunday morning parade. It's easy to attend the event on a budget. If you're planning to visit during this time, make sure to book your Lorient hostel in advance.
There is no beach in Lorient, but you can reach some by public transportation (bus or boat). You can also easily visit the very scenic isle of Groix by ferry. There are limited choices for hostels in Lorient (as seems to be the case in many French cities), and they tend to be situated in the suburbs of the city. You can still reach the main attractions from the Lorient hostels by public transportation, or better if you have your own means of transportation, you can visit the countryside or the famous megaliths of southern Morbihan which are less than 30km away