We present an internal collision attack against the new hash function Maraca which has been submitted to the SHA-3 competition. This attack requires 2^{237} calls to the round function and its complexity is lower than the complexity of the generic collision attack when the length of the message digest is greater than or equal to 512. It is shown that this cryptanalysis mainly exploits some particular differential properties of the inner permutation, which are in some sense in contradiction with the usual security criterion which guarantees the resistance to differential attacks.