I apologize in advance if this is a “repeat” post. I searched for 3M and didn’t find anything.
I found a wonderful waterproof tape on Amazon which is much more reasonable in price than some of the adhesive tapes that have been recommended in other postings. This tape has adhered my G6 sensor for over 2 weeks including trips to a whirlpool hot tub, showers, sweaty lawn work etc. It’s on sale for about $8.00 off currently… Highly recommended!
https://www.amazon.com/gp/product/B001H54S82/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1