Under the signaling mechanism, we aim to explore information sharing in a maritime supply chain consisting of one port with private forecast information and one risk averse carrier employing sustainability investment. To this end, we study two scenarios: non-information sharing and information sharing. Based on the different scenarios, we analyse the impacts of port forecast accuracy on decision-making and utility, and conclude that improving the forecast information accuracy is not always beneficial for the port and the carrier either. Meanwhile, we find that information sharing by the port is always beneficial for itself, but may be detrimental for the carrier, depending on the effectiveness of the sustainability investment. In addition, we propose two strategies to incentivize the port and the carrier to establish information sharing agreements. Finally, we validate above findings with some numerical analyses.