Following the great success of the 1st edition in 2013, we are pleased to announce the 2015 IEEE/OES Acoustics in Underwater Geosciences Symposium. More than 150 professionals, scientists and students from 18 different countries participated in RIO Acoustics 2013 .  Acoustics is the most effective way of investigating aquatic environments and ecosystems from land to open ocean with a wide diversity of applications. The technical programme of RIO Acoustics 2015 encompasses the newest techniques and technologies to solve challenges in ocean engineering, environmental protection, fisheries management, underwater mining and inland hydrometry.  We are looking forward to welcoming you and your co-workers during our symposium that will again take place in the wonderful city of Rio de Janeiro, from 29th to 31th July, 2015. The venue is the beautiful historical building of CPRM located in Urca neighbourhood at the foot of the emblematic Sugar Loaf mountain. Young investigators from South and Latin America are particularly encouraged to submit an abstract for oral or poster presentation.