I experienced an ant problem while staying at the Guesthouse. The staff were extremely kind and helpful, and moved us to another room in the Guesthouse but we experienced the same problem. After the second instance, they moved us into the main Hey Hotel. I would not recommend staying at the Guesthouse, but I would recommend staying at the Hey Hotel! The main hotel is clean, has air-conditioning, and is spacious. The Guesthouse is located behind the Hey Hotel so both their locations are great - walkable to Interlaken OST and Interlaken West station! The staff are also extremely kind, friendly, and accommodating :) The hotel also provides the free transit card in Interlaken if you ask for it. If I go back, I would stay at the Hey Hotel again, just not the Guesthouse.