Abstract: An efficient and error resilient underwater image coding algorithm is presented to resist the transmission errors of the underwater acoustic channels. The visual redundancy of underwater images is removed by a wavelet-based preprocessing technique according to the characteristics of underwater images. The low frequency coefficients are quantized and encoded by a fixed length algorithm, and the values and their corresponding positions of the important high frequency coefficients are coded separately, where the values are coded by a variable precision and fixed length algorithm, and their corresponding positions are coded by a position difference reduction-based RVLC（Reversible and Variable Length Coding） algorithm. Moreover, a packing and interleaving scheme and a placing scheme of the variable length coding blocks with respect to the fixed length acoustic channel packets are proposed to resist the transmission errors of the underwater acoustic channels. Error detection and concealment algorithms for low and high frequency coefficients are presented respectively. The experimental results show that the proposed coding algorithm provides both high coding efficiency and high error resilient performance, thus meeting the requirement of underwater image transmission via underwater acoustic channels.