Stanford Environmental Team
Here's a sample email you can copy/paste...
Hey!
Do you want to join me for a Sea Elephant tour at Año Nuevo State Park?
I went just recently and had a great time. The rest of the weekend tours for the season are booked, but groups of 3 or less can usually hop on a tour without a reservation.
If interested, let me know. This is the best time to go all year!