  We present a first detailed survey on underwater and air-water (A-W) wireless
communication networks (WCNs) that mainly focuses on the security challenges
and the countermeasures proposed to date. For clarity of exposition, this
survey paper is mainly divided into two parts. The first part of the paper
focuses on the state-of-the-art underwater and A-W WCNs whereby we outline the
benefits and drawbacks of the four promising underwater and A-W candidate
technologies: radio frequency (RF), acoustic, optical and magnetic induction
(MI), along with their channel characteristics. To this end, we also describe
the indirect (relay-aided) and direct mechanisms for the A-W WCNs along with
their channel characteristics. This sets the stage for the second part of the
paper whereby we provide a thorough comparative discussion of a vast set of
works that have reported the security breaches (as well as viable
countermeasures) for many diverse configurations of the underwater and A-W
WCNs. Specifically, we provide a detailed literature review of the various
kinds of active and passive attacks which hamper the confidentiality,
integrity, authentication and availability of both underwater and A-W WCNs.
Finally, we highlight some research gaps in the open literature and identify
security related some open problems for the future work.
