In a celebration of Britain's seas, Gillian Burke has ventured further down the Llyn Peninsular and explores a seagrass meadow. This threatened habitat holds so much importance for Britain's wildlife, and Gillian meets those trying their best to protect it. Meanwhile, Springwatch is poised on Swanage Pier to showcase an overlooked species that puts on quite the display under the waves in spring. Chris Packham and Michaela Strachan continue to explore the incredible array of wildlife at RSPB Arne in Dorset and provide updates on the live nests.