Amazon - 2 day delivery with Prime.Or pay for overnight.Can you have it shipped to your destination.https://www.amazon.com/s?k=gell+cell+batteries&crid=OXANHU89KAQ1&sprefix=gell+cell%2Caps%2C184&ref=nb_sb_ss_i_1_9
I learned the important battery question when I was looking for a replacement one.Don't look in the automotive section...Also, consider the strength of the battery you want. There is a formula for calculating how long a battery will last during normal use.I believe it's Voltage X Amps divided by power draw of device being used.So a 12v 10ah battery and a fish finder that draws 8 comes out to 12X10 divided by 8, or rather 15 hours of approximate run time.I could be wrong, but that's my rough guess at the formula I've read....
Have tried Cabelas, Dick's, and L.L. Bean while I'm on the road headed to my vacation destination in Maine from Indiana. All have 12 volt batteries for the big boats that are too heavy for the kayak.
Did you try "I need a battery for my portable fish finder/ice fishing depth finder at those stores?Some less experienced employees might not know about generally out of season product.Also ask at the counter where they sell the depth finders. Employees there may have a better knowledge.