Get on the river! 
Quite simply, it is the best way to explore the area. So ditch the car for the day and take the ferry up river, or hire a kayak and go explore! You won't believe how beautiful this stretch of water is and what there is to see, both natural and man made. There are numerous sheltered creeks to explore if you able to go 'off piste' or the open waters of Fal Estuary where you can sail, fish or bob about until the sun goes down. You won't be disappointed. 
Sadly the passenger ferry from Malpas/Truro is not currently running however you can pick it up from Trellisick Gardens, and journey up to Falmouth or St Mawes for a relaxing day out. 

Crabbing at the Pandora Inn! 
If you have younger members in the group there can be little more exciting than catching crabs off the floating jetty at the Pandora while the grown-ups sip on something chilled and chat away. Provided you catch the tide right (not low tide as it dries out) the children are pretty much guaranteed to catch a bucket full and if not there's always numerous other buckets to count & compare who's caught the biggest & fiercest! It's a must do on your visit.

Activities at Loe Beach! 
If you are looking to get out on the water and don't have a boat of your own then this is a great starting point. Kayaks, Paddle boards, Windsurfers, Sailing boats are all available to hire by the hour/day. If you are down for a while why not book yourself in for a course? There's a small gravel beach and cafe, but it's the activities that will keep you coming back.