Weymouth & Portland National Sailing Academy which hosted the 2012 Sailing Olympics, is exactly 1 mile from the cottage, along the Portland Beach Road, and its blue building can be seen easily from the bedroom window (anyone can go in to look around and for snacks).
The start of the Rodwell Trail at Ferrybridge passes very close to the cottage front door, and is part of the South West Coast Path. It follows the line of the old railway track, which, if you like walking (3/4 hour) takes you to the centre of Weymouth close to the inner harbour. Stop and explore Sandsfoot Castle and gardens on your way. Weymouth's sandy beach and safe, shallow sea bathing is just a 10-minute car ride away. (Details of masses of other attractions are in the cottage).
The cottage is only 200 yards from the shoreline of Portland Harbour and the little cove of Smallmouth Bay with rocks and a sandy beach. Just across the main Portland Road is the unique Fleet lagoon: a glass-bottomed boat from the jetty provides trips around this nature reserve, and the Chesil Beach visitor centre (with cafe) is just 15 minutes walk from the cottage, along the Portland Beach Road. In May and June, the grassy causeway is a mass of sea pinks (or thrift).
The cottage is an ideal location for those wanting to take part in watersports, Jurassic Coast Activities Watersports provide plenty of activities.
Mariner's View is ideally situated for exploring the coastline going west - to Abbotsbury and the Swannery, to Burton Bradstock, then on to Golden Cap and Lyme Regis (a favourite for fossil-hunters). Inland, there are beautiful walks around Hardy's Monument (Captain Hardy of Nelson's flagship HMS Victory, not the author Thomas Hardy): visit Upwey wishing well (the source of the River Wey): climb the grassy ramparts of Maiden Castle, an iron-age fort near Dorchester. Go eastwards to walk along the spectacular cliffs from Bowleaze to Redcliff Point, on to Ringstead, Lulworth and Durdle Door. In the autumn/winter go to Portland Bill and brace yourself against the spray of the Atlantic rollers crashing on the rocks. There is something here for everyone's tastes: lazy beach days, good walks, sailing.
Excellent places on Portland, The Crab House Cafe & Fleet Oyster Farm, a new restaurant at the Chesil Beach Visitor Centre (details in cottage), and a huge choice in Weymouth