Dårlig Ulv Stranden

Dårlig Ulv-Stranden — which, according to the non-Norwegian speaker, Rose Tyler, meant "Bad Wolf Bay" — was a bay fifty miles outside Bergen in Norway on the alternate Earth dubbed "Pete's World". It was notable for being the place where the Tenth Doctor and Rose said their first "final" farewells to each other. (DW: Doomsday) Rose would later call it the location of "the worst day of [her] life". (DW: Journey's End)

After the War in the Medusa Cascade, the Doctor took Rose back to Bad Wolf Bay with the Meta-Crisis Doctor and Jackie. The Meta-Crisis Doctor elected to stay with Rose, and they kissed while the Doctor departed. (DW: Journey's End)

Behind the scenes

To date, only the Dårlig Ulv-Stranden located on Pete's World has ever been seen or referenced; whether it also exists in the main Earth of the Doctor Who universe is unclear. According to Google Maps there is no Dårlig Ulv Stranden in Norway.
The beach was filmed in Southerndown beach, in South Wales, which was later used as the surface of Alfava Metraxis in The Time of Angels/Flesh and Stone.

Lost in translation

Norwegian speakers have noted several real world difficulties with the name.

Despite actor pronunciation in the episodes featured, it is actually pronounced "Dorli Ulv-Stranden".
In fact, the actual Norwegian equivalent to "bad wolf" is "slem ulv"; the adjective "slem" can be translated roughly as "naughty" or "bad (in behavior)", whereas the adjective "dårlig" can be translated as "poor in quality" or "feeling bad; as in feeling sick". The phrase "Who's afraid of the big, bad wolf?" is translated into Norwegian as: "Hvem er redd for den store, stygge ulven?" - thus: "Bad Wolf Bay" in Norwegian would be "Styggulvstrand" (since Norwegian toponyms rarely use the definite article). This, however, is a very old-fashioned use of the word "stygg", so the best translation would be more like "Slemulvstrand". "Dårlig Ulv Stranden" was clearly chosen for the pun on "Dalek". The choice of 'stranden' may also be a pun on the fact that Rose was stranded.
Strand actually means "beach" or "seacoast" not "bay". The Norwegian (bokmål) word for bay is "vik".
Another reason for the choice of using "Dårlig", is that "bad" roughly translates to the same word. "The food has gone bad" translates to "Maten er blitt dårlig", which supports the choice. The pronunciation in the show also resembles "Dalek" (Daleg), which could have some pun intent to it.
The Swedish translation of 'Bad Wolf' is "Stygga Vargen". "Dålig", a parallel of the Norwegian "Dårlig" actually gets it literally right. "Dåliga Vargen" means "Bad Wolf".