Looks like a sewer collapsed causing the hole.

Thank you for taking the time to “Report an Issue” via Doing Things for you ! The issue has been forwarded to Pinellas County Parks & Conservation Resources. They will inspect and take any necessary action.
Thank you for reporting! We are striving to improve our services. Please visit http://www.pinellascounty.org/surveys/parks to tell us how we are doing, Thank You!

Pinellas County Parks Department assigned this issue to Pinellas County Public Works- Roadway, Curb, Sidewalk & Bridge Maintenance

Thank you for taking the time to “Report an Issue” via Doing Things for you! Work Request 1801827 has been created by the Public Works Department. If you may have additional questions or concerns please contact our Customer Service Department at (727) 464-8900 or via email at publicworks@pinellascounty.org and reference the work request number.
We are striving to improve our services. Please take a moment to tell us how we are doing. Your input is greatly appreciated, thank you! link: www.pinellascounty.org/surveys/PublicWorks

Remember - just because the county "acknowledges" an issue doesn't mean they will act. My experience has been that the public can submit as many complaints as they wish concerning any issue but after a certain amount of time the county will arbitrarily close the complaint. They just shut it down. On a few rare occasions, if enough taxpayers contact their county represemtatives something may get done. BTW, the county administrator and public works officials will simply ignore any communications.