When discussing underground investment opportunities, it is important to note that these investments are often unregulated and come with a high degree of legal and financial risk. Here are some types of investments that are generally considered high risk and high return, but are not recommended: 1. **Cryptocurrency**: While many cryptocurrency exchanges and investments are legal, some projects involving newly issued tokens or unproven projects may be underground in nature. These investments may bring high profits, but the market is extremely volatile and prone to fraud. 2. **ICO and DeFi Projects**: Initial Coin Offerings (ICOs) and Decentralized Finance (DeFi) projects may bring huge profits, however, many projects lack transparency and there is a risk of running away or regulatory crackdowns. 3. **Underground Casinos or Illegal Gambling**: These places may promise high returns, but they are accompanied by legal risks and fraud risks. 4. **Art Smuggling**: Rare artworks can fetch extremely high profits on the black market, but participating in them is illegal and involves serious legal consequences. 5. **Drug or Arms Dealing**: While the profits are extremely considerable, these are illegal activities and face significant legal risks and ethical issues. 6. **Tax evasion investment**: Some investment schemes may involve illegal tax loopholes, which also face legal risks. It is recommended to conduct in-depth research on any investment opportunities and consult professional financial advisors or legal advisors to avoid unnecessary legal disputes or financial losses. While pursuing high profits, it is necessary to carefully assess the corresponding risks.