The waters around Strumble Head, Skomer and Dale are among ten sites to be considered as highly protected Marine Conservation Zones (MCZ).
Welsh Government Environment Minister John Griffiths announced last week the first consultation exercise for selecting MCZs - with just three or four to be selected.
The consultation has been welcomed by the Countryside Council for Wales, one of a number of technical advisory groups involved in the selection of potential sites.
The potential sites have been identified because they support a wide variety of habitats and associated wildlife.
Pembrokeshire's candidates are an area of 4.1km squared south west of Strumble Head - chosen for its numerous different habitats and rocky reefs supporting a rich mix of sponge species; around Skomer Island (10.5km squared) including much of Skomer Marine Nature Reserve and the many species recorded in the water; and nearly 3km squared of water at Dale and its muddy habitats such as the muddy gravels on the shore which support a wide range of species of worms and cockles.
Mr Griffiths said: "The Welsh Government now has greater powers to protect Wales' important marine environment.
"We plan to use these new powers to strengthen and supplement our existing marine protected areas in Wales with new Marine Conservation Zones.
"The idea is that this approach will maximise the contribution that the areas make to ecosystem recovery and resilience and will help us to develop our understanding of how ecosystems naturally function."
The process that has been used to identify the potential sit e options is new and focuses on how the whole site contributors to the marine environment and ecosystem recovery.
CCW chief scientist Dr David Parker added: "It's vital that our seas are healthy and managed in a sustainable way so that we can continue to enjoy and benefit from their goods and services for many generations to come. Highly protected MCZs have a role to play in achieving this."
To participate in the consultation process and contribute to the final site selection visit www.wales.gov.uk/marine before July 31st.